CN103591982B - A kind of monitoring method of electric power tunnel structure problem - Google Patents

Abstract

The invention relates to a monitoring method for structural problems of electric power tunnels, comprising: setting monitoring items according to tunnel conditions; Sections are key monitoring sections; Type II sections are general monitoring sections; Type III sections are sections for which monitoring items are added for construction settlement records; corresponding monitoring items are set according to different monitoring section types; Corresponding monitoring components; the monitoring data of the monitoring components are transmitted to the digital processing platform for analysis and processing. Compared with the existing technology, the present invention not only designs and arranges monitoring sections, but also adds monitoring sections to control settlement and convergence deformation at dangerous places according to the settlement monitoring data, which can dynamically monitor tunnel structural problems and provide accurate health status data in real time , providing services for operation and maintenance intuitively and clearly.

Description

A monitoring method for structural problems in power tunnels

technical field

The invention relates to the field of remote automatic monitoring of tunnels, in particular to a monitoring method for structural problems of power tunnels.

Background technique

The power tunnel is a power tunnel project to develop the scale of the power cable tunnel network in the urban area. Most tunneling projects require multiple passes through important structures throughout the entire process. Due to the complex relationship of the underground space, the structural safety is greatly affected by the surrounding environment, and due to the influence of the structural characteristics of the power tunnel itself, it is necessary to analyze these characteristics clearly before formulating the monitoring plan and maintenance system.

For the analysis of the long-term operation of the power tunnel, the foreseeable problems are as follows:

(1) The line mileage is long, the underground space relationship is complex, and the mutual influence of different structures is long-term and complicated;

(2) According to the existing engineering statistics, under long-term operating conditions, soft soil tunnels may have problems such as uneven settlement, segment opening, segment displacement, bolt shedding, and material deterioration that endanger structural safety, threatening the safety and security of operation. Stablize;

(3) The crossing of the power tunnel includes not only the crossing of other existing tunnel lines, but also the crossing of the planned and proposed lines. It is foreseeable that after the power tunnel is put into operation, other projects will still be constructed around it in the future , and the excavation of soil and the construction of structures are bound to have impacts such as soil disturbance on the surrounding environment of electric power, threatening the safe operation of structures;

(4) In view of the supporting role played by the power system in the operation of the city, the safety and reliability of the power tunnel not only affects production and life, but is often related to the normal operation of all parts of the city, and may even cause the city to be paralyzed as a whole. "Take a hair and move the whole body." Therefore, to ensure its safe and effective operation and to avoid adverse social impacts caused by safety accidents, stricter management and maintenance measures are required than ordinary soft soil tunnels.

Based on engineering practice and theoretical analysis, the unfavorable factors affecting the safety of tunnel operation period are divided into the following categories;

(1) Water and soil pressure is too large or too small

As an external load directly acting on the tunnel structure, the water and soil pressure determines the stress state of the main structure of the tunnel. Any changes in environmental loads (loading and unloading caused by nearby construction, sudden disasters, etc.) will be expressed through changes in water and soil pressure. When the water and soil pressure is too large, it may lead to uneven settlement of the tunnel structure and even structural damage. When the water and soil pressure is too small and the buoyancy is too large, the buoyancy of the tunnel will seriously affect its safety, applicability and durability. At present, earth pressure cells can be used in engineering to measure water and soil pressure.

(2) The internal force of the structure is too large

Due to the long-term load, there will be a fatigue effect of stress relaxation. When the load is uneven, some components will be unfavorably stressed and cause local damage, thus threatening the safety of tunnel operation. At present, the embedding of steel stress gauges can be used in engineering to measure the internal force of structures.

(3) Segment dislocation

There are 6 displacements of the segment along the longitudinal seam and the annular seam. The causes of the disease include the opening of the capping block (longitudinal seam) due to section deformation, the opening of the annular seam caused by uneven settlement, assembly errors during construction, jack extrusion and Changes in external loads (earthquakes, construction, etc.), generally where the position is too large will be accompanied by joint failure, resulting in a greatly increased incidence of water leakage. Existing monitoring methods include a one-way displacement meter for measuring joint opening and a three-way displacement meter system for measuring three-dimensional displacement of segments.

(4) Section deformation

The factors that cause the convergence deformation of the section are generally considered to be of two types: load factors and uneven settlement factors. Load factors include deformation caused by construction (jack extrusion, excessive grouting pressure, etc.), and external load factors during the operation period (long-term effects of existing loads and sudden loads such as earthquakes and external construction). Uneven settlement will cause uneven longitudinal force on the tunnel. Under the original constraints, the section will be flattened in some positions. At present, the method of evaluating the convergence deformation of the section in engineering is to measure the segment displacement at the horizontal diameter.

(5) Longitudinal settlement

The causes of general settlement are mainly the consolidation settlement and sub-consolidation settlement of the soil, while the causes of uneven settlement can be divided into three types: uneven load, uneven soil properties, and uneven structural stiffness. Uneven settlement will lead to the occurrence of several diseases such as section deformation, segment dislocation, and bolt deformation. When the longitudinal deformation is too large, not only the applicability of the structure will be affected, but also its durability and safety will be affected. The settlement can be monitored from the structure itself, and the settlement of layered soil can be monitored at the position where conditions permit.

Therefore, the long-term monitoring scheme of the power tunnel should meet the following basic requirements: the monitoring parameters have index significance to reflect the real situation of the tunnel; the monitoring items should collect data automatically as much as possible; combined with the actual progress of the project; feasibility.

Contents of the invention

The purpose of the present invention is to provide a monitoring method for structural problems of electric power tunnels in order to overcome the defects of the above-mentioned prior art.

The object of the present invention can be achieved through the following technical solutions: a monitoring method of electric tunnel structure problem, it is characterized in that, the method comprises the following steps:

1) Determine the monitoring items according to the tunnel conditions;

2) According to the different importance levels of monitoring throughout the tunnel, the types of monitoring sections are divided into three types: I, II, and III. Type I sections are key monitoring sections; Type II sections are ordinary monitoring sections; Type III sections are for construction Settlement records increase the section of monitoring items;

3) Select corresponding monitoring items according to different monitoring section types;

4) According to the condition of the tunnel, deploy corresponding monitoring components for the monitoring items;

5) The monitoring data of the monitoring components are transmitted to the digital processing platform for analysis and processing.

The monitoring items described in step 1) include the opening of the segment joints, the external earth pressure of the tunnel, the internal force of the segment joint bolts, the convergence deformation inside the tunnel, the settlement of the longitudinal line of the tunnel, the horizontal displacement of the soil layer, the settlement of the layer layer, the tunnel Structural hoop strain, tunnel plane displacement.

The type I section described in step 2) is the crossing section and the expected crossing section with complex underground space relationships, where the structure is most strongly and sensitively affected by external loads, and needs to be monitored; the type II section has the smallest radius of curvature along the longitudinal line , where the deformation is more obvious, which belongs to the node position; the category III section refers to the construction settlement record, and in the section where the settlement and differential settlement are more serious, two types of monitoring items, settlement and section convergence deformation, are added.

Step 3) The corresponding monitoring items set according to different monitoring section types refer to the monitoring items of Class I section including segment joint opening, tunnel external earth pressure, segment joint bolt internal force, tunnel internal convergence deformation, tunnel longitudinal The settlement of the line, the horizontal displacement of the soil layer, the settlement of the stratum layer, the circumferential strain of the tunnel structure, and the plane displacement of the tunnel; the monitoring items of the type II section include the opening of the segment joint, the internal force of the segment joint bolt, and the settlement of the longitudinal line of the tunnel. , tunnel structure hoop strain, tunnel plane displacement; monitoring items for category III sections include tunnel internal convergence deformation and tunnel longitudinal settlement.

Step 4) The deployment of corresponding monitoring elements according to the monitoring items includes the deployment of a joint gauge for monitoring the opening of the segment joints; the deployment of an earth pressure box for monitoring the external earth pressure of the tunnel; the deployment of a bolt stress tester for monitoring the internal force of the segment joint bolts; and the deployment of a bolt stress tester for monitoring the interior of the tunnel Deploy hooks and convergence rulers for convergence deformation; monitor the settlement of the longitudinal line of the tunnel and deploy a total station; monitor the horizontal displacement of the overlying soil layer by layer and install an automatic inclinometer; monitor the layered settlement of the stratum; Strain gauges; total stations are used to monitor the plane displacement of the tunnel.

The above-mentioned layout joint gauge refers to installing four circumferential joint gauges at 0, 90, 180, and 270 degrees of the tunnel circumference, and installing six axial joint gauges at six joints;

Arrangement of pressure cells means that a total of three pressure cells are arranged on each monitoring section, which are respectively located at the top, left level and right level directly above the tunnel;

Arrangement of bolt stress tester refers to the arrangement of bolt stress tester on the bolts at the joints of the monitoring section;

Laying the convergence ruler refers to laying out the convergence measuring points along the circumference of the section in the end-to-end connection;

The deployment of automatic inclinometers refers to the deployment on the outside side of the tunnel, and the buried depth is required to reach the bottom of the tunnel;

The laying of layered settlement instruments refers to laying on the outside side of the tunnel, and the buried depth is required to reach the bottom of the tunnel;

The arrangement of strain gauges refers to the circular arrangement at four points of 0, 90, 180, and 270 degrees inside the tunnel, and a total of four strain gauges are arranged on each monitoring section;

The deployment of electronic total stations refers to the selection of datum points in accordance with the specifications, and they are arranged near the working well, that is, the wind shaft. The measuring stations are arranged in the tunnel, and each measuring station must be able to see at least one other measuring station in the tunnel. Measuring stations should be arranged, and reflective sheets should be installed at the measuring points. There are four reflective sheets installed at the positions of 0, 90, 180, and 270 degrees inside the tunnel. The measuring points are evenly distributed along the entire line, and a measuring point is set every ten meters.

Compared with the prior art, the present invention proposes an operation monitoring method for the possible damages that the engineering environment where the power tunnel is located in, and designs and arranges monitoring points for different monitoring items of the monitoring section, and according to the settlement monitoring data of the construction completion period , adding monitoring sections to control settlement and convergence deformation at dangerous places. The method of the invention can dynamically monitor tunnel structural problems, provide comprehensive health status evaluation and early warning in real time, and provide intuitive and clear services for operation and maintenance.

detailed description

The present invention will be described in detail below in conjunction with specific embodiments.

A monitoring method for power tunnel structural problems, characterized in that the method comprises the following steps:

1) Determine the monitoring items according to the tunnel conditions;

2) According to the different importance levels of monitoring throughout the tunnel, the types of monitoring sections are divided into three types: I, II, and III. Type I sections are key monitoring sections; Type II sections are ordinary monitoring sections; Type III sections are for construction Settlement records increase the section of monitoring items;

3) Select corresponding monitoring items according to different monitoring section types;

4) According to the condition of the tunnel, deploy corresponding monitoring components for the monitoring items;

5) The monitoring data of the monitoring components are transmitted to the digital processing platform for analysis and processing.

The monitoring items described in step 1) include the opening of the segment joints, the external earth pressure of the tunnel, the internal force of the segment joint bolts, the convergence deformation inside the tunnel, the settlement of the longitudinal line of the tunnel, the horizontal displacement of the soil layer, the settlement of the layer layer, the tunnel Structural hoop strain, tunnel plane displacement.

The type I section described in step 2) is the crossing section and the expected crossing section with complex underground space relationships, where the structure is most strongly and sensitively affected by external loads, and needs to be monitored; the type II section has the smallest radius of curvature along the longitudinal line , where the deformation is more obvious, which belongs to the node position; the category III section refers to the construction settlement record, and in the section where the settlement and differential settlement are more serious, two types of monitoring items, settlement and section convergence deformation, are added.

Step 3) The corresponding monitoring items set according to different monitoring section types refer to the monitoring items of Class I section including segment joint opening, tunnel external earth pressure, segment joint bolt internal force, tunnel internal convergence deformation, tunnel longitudinal The settlement of the line, the horizontal displacement of the soil layer, the settlement of the stratum layer, the circumferential strain of the tunnel structure, and the plane displacement of the tunnel; the monitoring items of the type II section include the opening of the segment joint, the internal force of the segment joint bolt, and the settlement of the longitudinal line of the tunnel. , tunnel structure hoop strain, tunnel plane displacement; monitoring items for category III sections include tunnel internal convergence deformation and tunnel longitudinal settlement.

Step 4) The deployment of corresponding monitoring elements according to the monitoring items includes the deployment of a joint gauge for monitoring the opening of the segment joints; the deployment of an earth pressure box for monitoring the external earth pressure of the tunnel; the deployment of a bolt stress tester for monitoring the internal force of the segment joint bolts; and the deployment of a bolt stress tester for monitoring the interior of the tunnel Deploy hooks and convergence rulers for convergence deformation; monitor the settlement of the longitudinal line of the tunnel and deploy a total station; monitor the horizontal displacement of the overlying soil layer by layer and install an automatic inclinometer; monitor the layered settlement of the stratum; Strain gauges; total stations are used to monitor the plane displacement of the tunnel.

The above-mentioned layout joint gauge refers to installing four circumferential joint gauges at 0, 90, 180, and 270 degrees of the tunnel circumference, and installing six axial joint gauges at six joints;

Arrangement of pressure cells means that a total of three pressure cells are arranged on each monitoring section, which are respectively located at the top, left level and right level directly above the tunnel;

Arrangement of bolt stress tester refers to the arrangement of bolt stress tester on the bolts at the joints of the monitoring section;

Laying the convergence ruler refers to laying out the convergence measuring points along the circumference of the section in the end-to-end connection;

The deployment of automatic inclinometers refers to the deployment on the outside side of the tunnel, and the buried depth is required to reach the bottom of the tunnel;

The laying of layered settlement instruments refers to laying on the outside side of the tunnel, and the buried depth is required to reach the bottom of the tunnel;

The arrangement of strain gauges refers to the circular arrangement at four points of 0, 90, 180, and 270 degrees inside the tunnel, and a total of four strain gauges are arranged on each monitoring section;

The deployment of electronic total stations refers to the selection of datum points in accordance with the specifications, and they are arranged near the working well, that is, the wind shaft. The measuring stations are arranged in the tunnel, and each measuring station must be able to see at least one other measuring station in the tunnel. Measuring stations should be arranged, and reflective sheets should be installed at the measuring points. There are four reflective sheets installed at the positions of 0, 90, 180, and 270 degrees inside the tunnel. The measuring points are evenly distributed along the entire line, and a measuring point is set every ten meters.

The test method for each monitoring item is as follows:

1) Segment seam opening

Connect the seam measuring instrument to the seam, the first frequency test value of the instrument is used as the initial frequency, and the frequency received by the sensor each time is used as the current frequency test value, through the comparison of the frequency test value and the initial value Calculate the opening amount of the seam according to the relevant formula, "+" means the seam is open, and "-" means the seam is closed.

2) External earth pressure of the tunnel

As the earth pressure outside the tunnel directly acts on the tunnel structure, it is the direct cause of tunnel structure damage. The change of external earth pressure is the precursor of tunnel structure damage. Therefore, monitoring the earth pressure outside the tunnel can ensure the safety of the tunnel structure in advance. The performance and deformation of the tunnel structure can be predicted.

Select a stable earth pressure cell, stick the pressure cell on the outside of the segment and lay it out together with the segment assembly or through drilling. After the instrument is installed, the frequency measured by the frequency meter for the first time is recorded as the initial frequency. The obtained frequency is the current test value. By comparing with the initial frequency and using the corresponding conversion formula, the change of earth pressure in each measurement can be obtained.

3) Internal force of segment joint bolts

The segment joint is a relatively weak link in the tunnel structure, so the internal force of the joint bolts should also be one of the long-term monitoring items of the tunnel. This program determines the force of the bolts by measuring the strain of the bolts.

The bolt stress tester uses ultrasonic reflection technology to accurately and quickly measure the stress and strain of the bolt after it is fastened according to the relative relationship between the length and stress of the bolt under different stress conditions and its sound velocity propagation. In application, the probe is placed at both ends of the bolt to test its sound waves to convert the strain of the bolt and calculate the stress of the bolt. The frequency measured each time after installation is used as the measured value, and the variation trend of the internal stress of the bolt can be obtained by comparing the measured value with the initial value.

4) Convergent deformation inside the tunnel

The convergent deformation inside the tunnel reflects the stress of the structure to a large extent, and excessive convergent deformation will affect the function of the structure, so it is necessary to monitor the convergent deformation inside the tunnel.

The distance change of a certain position of the tunnel is measured by the hook, and then the convergence deformation of the tunnel cross section is calculated according to the geometric analysis of the installation position of the instrument.

5) Longitudinal settlement of the tunnel

Tunnel settlement in soft soil tunnels is the main cause of tunnel damage. Excessive settlement or uneven settlement will cause deformation of the tunnel structure, cracks and joint opening and other diseases.

The test system is composed of a reference point measuring terminal and a series of measuring point terminals. By comparing the monitoring value of the measuring point with the monitoring value of the reference point, the elevation difference of the measuring point relative to the reference point can be obtained, and then the overall settlement and settlement of the tunnel can be obtained. Uneven settlement.

6) Layered horizontal displacement of the overlying soil layer

After drilling and laying out the inclinometer pipe, installing the inclinometer and automatic detection device, each measurement can be based on the coordinates of the top of the inclinometer pipe to obtain the horizontal position of the stratum, and then obtain the stratification of the overburden of the tunnel Horizontal displacement.

7) Layered settlement of soil

Settlement pipes are laid out in boreholes, backfilled with fine sand, and the elevation of pipe mouth is measured with a level gauge. At the same time, the first measurement value of the rigid ring position is used as the initial value, and each subsequent test value is used as the current measurement result, and then compared with By comparing the initial values, the layered subsidence of the formation can be obtained.

8) Circumferential strain of pipe jacking section

The strain gauge is installed before the segment is assembled, and the measured frequency is used as the initial value, and the measured frequency after assembly is used as the measured value, and the strain at the corresponding position of the segment can be obtained by comparing with the initial value.

9) Tunnel plane displacement

Select a reference point near the working well or relay station as required, and set up multiple measuring stations along the tunnel. The position of the measuring station can be measured through the reference point, and then set monitoring sections at certain distances in the tunnel, and install reflective sheets on the monitoring sections , the position of the measuring point is determined by the corresponding measuring station.

Claims (6)

1. A monitoring method for power tunnel structural problems, characterized in that the method may further comprise the steps: 1) Determine the monitoring items according to the tunnel conditions; 2) According to the different monitoring importance levels throughout the tunnel, the types of monitoring sections are divided into three types: I, II, and III. Type I sections are key monitoring sections; Type II sections are ordinary monitoring sections; Type III sections are for construction Subsidence records increase the section of monitoring items; 3) Select corresponding monitoring items according to different monitoring section types; 4) According to the condition of the tunnel, deploy corresponding monitoring components for the monitoring items; 5) The monitoring data of the monitoring components are transmitted to the digital processing platform for analysis and processing. 2. The monitoring method of a kind of electric power tunnel structure problem according to claim 1, it is characterized in that, the monitoring item described in step 1) includes segment seam opening amount, tunnel external earth pressure, segment joint bolt internal force, tunnel Internal convergence deformation, settlement of tunnel longitudinal line, horizontal displacement of soil stratification, settlement of stratum stratification, circumferential strain of tunnel structure, tunnel plane displacement. 3. The monitoring method of a kind of electric power tunnel structure problem according to claim 2, it is characterized in that, step 2) described I class cross section is the crossing section and the expected crossing section with complex underground space relationship, where the structure is affected by the outside world The impact of load is the most intense and sensitive, and it needs to be monitored; the category II section is the smallest radius of curvature along the longitudinal line, where the deformation is more obvious and belongs to the node position; the category III section refers to the construction settlement records. For sections with severe differential settlement, two types of monitoring items, settlement and cross-section convergence deformation, are added. 4. The monitoring method of a kind of power tunnel structure problem according to claim 2, it is characterized in that, step 3) described according to different monitoring section types selects corresponding monitoring item and refers to the monitoring item of I class section and comprises segment Joint opening, tunnel external earth pressure, segment joint bolt internal force, tunnel internal convergence deformation, tunnel longitudinal settlement, soil layer horizontal displacement, stratum layer settlement, tunnel structure hoop strain, tunnel plane displacement; Class II The monitoring items of the section include the expansion of segment joints, the internal force of segment joint bolts, the settlement of the longitudinal line of the tunnel, the circumferential strain of the tunnel structure, and the plane displacement of the tunnel; the monitoring items of category III sections include the convergence deformation inside the tunnel and the settlement of the longitudinal line of the tunnel . 5. The monitoring method of a kind of electric power tunnel structure problem according to claim 2, it is characterized in that, step 4) described according to monitoring item layout corresponding monitoring element comprises monitoring segment seam opening amount and laying joint gauge; Monitoring tunnel Layout earth pressure box for external earth pressure; Layout bolt stress tester for monitoring the internal force of segment joint bolts; Layout hooks and convergence rulers for monitoring tunnel internal convergence deformation; Layout total station for monitoring tunnel longitudinal settlement; Layout for monitoring horizontal displacement of soil layers Automatic inclinometer; layered settlement instrument for monitoring layered settlement of stratum; strain gauge for monitoring tunnel structure circumferential strain; total station for monitoring tunnel plane displacement. 6. A monitoring method for structural problems of an electric power tunnel according to claim 5, characterized in that, said laying seam gauge means to install circumferential seam measuring at 0, 90, 180, and 270 degrees of the tunnel circumference A total of four axial joint gauges are installed at the six seams; The arrangement of earth pressure cells refers to the arrangement of three earth pressure cells on each monitoring section, which are located at the top, left level and right level of the tunnel, respectively; Laying the bolt stress tester refers to laying the bolt stress tester on the bolts at the joints of the monitoring section; Laying the convergence ruler refers to laying out the convergence measuring points along the circumference of the cross-section in the end-to-end connection; The deployment of automatic inclinometers refers to the deployment on the outside side of the tunnel, and the buried depth is required to reach the bottom of the tunnel; Deployment of layered settlement instruments refers to the deployment on the outer side of the tunnel, and the burial depth is required to reach the bottom of the tunnel; The arrangement of strain gauges refers to the circular arrangement at four points of 0, 90, 180, and 270 degrees inside the tunnel, and a total of four strain gauges are arranged on each monitoring section; The layout of the total station refers to selecting the reference point according to the specifications, and laying it near the working well, that is, the wind shaft. The measuring station is arranged in the tunnel, and each measuring station must be able to see at least one other measuring station in the tunnel. The measuring stations are arranged, and reflective sheets are installed at the measuring points. There are four reflective sheets installed on the inner side of the tunnel at 0, 90, 180, and 270 degrees. The measuring points are evenly distributed along the entire line, and a measuring point is set every ten meters.