CN101324062A - Method and device for testing mud pressure of retaining wall in trench construction of underground diaphragm wall - Google Patents

Abstract

The invention relates to a method and a device for testing the mud pressure of an underground diaphragm wall in groove-forming construction of an underground diaphragm wall in the technical field of construction. In the present invention, a measuring rope with a scale is bound on the hook of the collar; a pressure sensor is installed in the collar; the data transmission wire of the pressure sensor is drawn out from the slot hole of the collar, together with the measuring rope bound on the collar , connected to the lifting frame; slide the pressure sensor into the tank section through the lifting frame, and read the pressure sensor; lift the pressure sensor upwards, and repeat the reading of the pressure sensor; the mud pressure results measured at the same depth Carry out the average, draw the scatter point data of the relationship between depth and mud pressure, and fit the scatter point data to obtain the mud pressure distribution at different depths in the groove section. The invention can more accurately measure the pressure of the retaining wall mud during the groove-forming process of the underground continuous wall, and the test result is accurate and reliable.

Description

Method and device for testing mud pressure of retaining wall in trench construction of underground diaphragm wall

technical field

The invention relates to a testing method and a device in the technical field of construction engineering, in particular to a testing method and a device for protecting wall mud pressure in groove-forming construction of an underground diaphragm wall.

Background technique

The so-called underground diaphragm wall construction method is to use a special groove-forming machine in advance, along the deep foundation or the periphery of the underground structure, use bentonite thixotropic mud to protect the wall, excavate a groove section with a certain depth and section, and then place it in the groove section. into a prefabricated steel cage, and use underwater pouring concrete to form wall sections, such continuous construction, so that the wall sections are connected to each other to form a complete underground continuous wall with soil retaining and waterproof functions, and can also be used as the main underground structure or part thereof. Because this construction method can excavate deep grooves of any depth and section, it can build underground continuous walls with different depths, widths, shapes, thicknesses and strengths according to design requirements. During construction, no matter when the groove is formed or after the groove is completed, the groove section must be filled with thixotropic mud, and the liquid level of the mud must be at least 0.5m higher than the groundwater level. Keep the soil of the groove wall stable, so that there will be no danger of the groove wall collapsing before the wall is built.

The function mechanism of the mud retaining wall is as follows: the specific gravity of the mud is greater than that of the groundwater, and the liquid level is higher than the groundwater level, so that the liquid column pressure of the mud is sufficient to balance the groundwater and soil pressure, and becomes a liquid pressure support for the soil of the groove wall. At the same time, the mud pressure enables the mud to infiltrate into the pores of the soil on the tank wall, fill them, and form a layer of mud skin with a dense structure and low water permeability on the surface of the tank wall, so that the soil on the tank wall will change from the original medium with high dispersion. The cementation forms a whole with thin film properties, which further maintains the stability of the groove wall. In addition, the mud also has the functions of carrying ballast, cooling and lubricating, and can be used as a medium for soil transportation in trenching construction, improving construction efficiency and prolonging the service life of construction machinery.

Therefore, in the construction process of the underground diaphragm wall, in order to ensure the groove quality of the diaphragm wall and the stability of the groove wall, a series of requirements are put forward for the performance and technical indicators of the mud on site, and inspection and control should be carried out during the mud preparation and groove construction . The main performance indicators of mud include: specific gravity, viscosity, sand content and PH value, etc. Among them, the mud specific gravity can indirectly reflect the pressure of the mud on the soil of the groove wall, so the engineering field usually uses a mud hydrometer to measure the mud specific gravity, and then indirectly reflects the pressure of the mud on the groove wall. The disadvantages of this indirect method of measuring the mud pressure are: ① Due to the use of a conventional mud tank with a movable cover to sample the mud from the tank section and test the mud specific gravity, there are inevitably problems of mud leakage and mud mixing during the sampling process , there are problems of large variability of test results and low precision, which will affect the test accuracy of mud pressure; ②Due to the need to sample mud from different depths in the tank section, the sampling workload is heavy, and the sampling that can be obtained within a limited time The number of points is limited, so the test efficiency is low, which has a certain impact on the construction progress of the project.

After searching the prior art documents, it was found that Chinese patent application number 200410005525.0, title of invention: a method and device for receiving and detecting mud pressure pulse signals, publication number: CN1657740, the patent reads as: the present invention provides a method and device for receiving and detecting mud pressure pulse signals. A method and device for a mud pressure pulse signal, which receives a signal containing mud pressure pulse code information transmitted from a channel; performs low-pass filtering on the received signal; removes the DC component of the low-pass filtered signal; The noise in the received signal establishes a noise estimate; performs system synchronization word detection correlation operations on the signal with the DC component removed; performs adaptive filtering on the signal with the DC component removed; uses code bit correlation operations to judge code bits, and according to the code The protocol demodulates data from the received signal. Even in the case of severe noise environment, useful signals can be extracted from the received information seriously polluted by noise; meanwhile, the method can be realized through the device, and it is compatible with several downhole measuring instruments while drilling. The invention is a testing method and instrument while drilling in drilling engineering, which can be applied to drilling fluid pressure test signal processing in geological exploration and development, and the test object is the mud pressure pulse used for the measurement while drilling, rather than the mud pressure itself. This method cannot be applied to the mud pressure test of retaining walls formed into trenches in underground diaphragm walls. The engineering fields and test objects of the two are completely different and cannot be used universally.

Contents of the invention

The present invention aims at the deficiencies in the above-mentioned prior art, and proposes a method and device for testing the mud pressure of the retaining wall in the groove-forming construction of the underground diaphragm wall, which overcomes the poor accuracy of the test results and the poor accuracy of the obtained test results in the conventional mud hydrometer method. The disadvantage of limited number of sampling points has the advantages of high monitoring accuracy and a large number of monitoring data points, which greatly improves the data accuracy and test efficiency of on-site testing, and has strong practicability.

The present invention is achieved through the following technical solutions:

The method for testing the retaining wall mud pressure in the trench construction of the underground diaphragm wall involved in the present invention comprises the following steps:

The first step is to prepare a metal protective collar with a slot on the upper end, and tie a measuring rope with a scale on the hook of the collar;

The second step is to loosen the screws on the outside of the collar, install the pressure sensor in the collar, and tighten the screws to fix the pressure sensor;

The third step is to lead the data transmission wire of the pressure sensor out from the slot hole of the collar, lead out together with the measuring rope bound on the collar, and connect it to the lifting frame erected on the ground;

The fourth step is to slowly slide the pressure sensor into the tank section from the mud liquid level through the roller of the lifting frame, and measure and read the pressure sensor at every set vertical interval until the pressure sensor slides to the bottom of the tank section;

Step 5: Starting from the bottom of the tank section, slowly lift the pressure sensor upwards through the rollers of the lifting frame, and repeat the reading of the pressure sensor at set vertical intervals until the pressure sensor is lifted to the mud level;

The sixth step is to average the mud pressure results measured at the same depth, draw the scattered point data of the relationship between depth and mud pressure, and fit the scattered point data to obtain the mud pressure distribution at each depth in the groove section.

The device for testing mud pressure of retaining wall in trench construction of underground diaphragm wall according to the present invention includes a lifting system and a testing system, and the lifting system includes a protective collar, a measuring rope, and a lifting frame. The test system includes a pressure sensor, a data transmission wire, and a data acquisition instrument. The pressure sensor is set in the protective sleeve, and the protective sleeve is provided with a slot hole. The data transmission wire of the pressure sensor is drawn out from the slot and connected to the data acquisition instrument. There are elastic screws on the outside of the protective sleeve for fixing the pressure. sensor. The upper part of the protective collar is connected with a hook, the lifting frame is mounted on the continuous wall groove section, the lifting frame is equipped with a wheel, the lower end of the measuring rope is bound to the hook, and the upper end is fixed and coiled on the wheel of the lifting frame.

The inner diameter of the protective collar is larger than that of the pressure sensor, so as to ensure that the pressure sensor can be smoothly inserted into the protective collar.

The inner diameter of the slot hole on the upper part of the protective collar is larger than the diameter of the pressure sensor data wire.

The measuring rope has a scale to ensure that the depth of the pressure sensor in the groove section can be read.

The lifting frame has four fulcrums, which are respectively mounted on both sides of the continuous wall groove section, and wheels are installed on the lifting frame, which can control the depth of the pressure sensor, the speed of the pressure sensor sliding and lifting.

The pressure sensor is a vibrating wire pressure gauge.

The data transmission wire is a two-core measurement cable, which can be measured and read by a data acquisition instrument. The data transmission wire extends from the pressure sensor to the ground to ensure that the tester can read the data.

The data acquisition instrument is a palm-sized pocket frequency readout instrument used by a vibrating wire sensor.

The present invention puts the pressure sensor in the groove section, and through the rotation of the wheel, the pressure sensor is slowly slid down from the mud liquid surface below the mud liquid surface in the groove section, and the mud pressure is measured and read at certain vertical intervals until The pressure sensor slides to the bottom of the tank section, and then starts from the bottom of the tank section, and then slowly lifts the pressure sensor from bottom to top, and repeats the pressure measurement at certain vertical intervals until the pressure sensor is raised to the height of the mud liquid level. When the pressure sensor slides and lifts, it is necessary to ensure that the data transmission wire of the pressure sensor remains in a slack state to prevent the data transmission wire from being pulled, that is, the weight of the protective collar and the pressure sensor is all borne by the measuring rope. Average the pressure values measured at the same depth during the descent and ascension of the pressure sensor to reduce the reading error caused by one measurement. Finally, the scatter data graph between the depth and the mud pressure is drawn, and the measured scatter data is used for curve fitting to obtain the mud pressure at different depths in the groove section.

The invention is simple, easy to install, simple to operate, and high in testing efficiency, and is applied in the mud pressure test in the trench construction of large-depth underground diaphragm walls in Shanghai area, and has achieved remarkable effects through engineering practice verification.

Description of drawings

Fig. 1 is the schematic structural diagram of the test device adopted in the embodiment of the present invention;

Fig. 2 is the depth and the mud pressure relational graph that the embodiment of the present invention D15 groove section test obtains;

Fig. 3 is the curve diagram of the relationship between depth and mud pressure obtained by the D31 groove section test of the embodiment of the present invention;

Fig. 4 is a curve diagram of the relationship between depth and mud pressure obtained from the test of the DQC2b groove section of the embodiment of the present invention.

Detailed ways

The embodiments of the present invention are described in detail below in conjunction with the accompanying drawings: this embodiment is implemented on the premise of the technical solution of the present invention, and detailed implementation methods and specific operating procedures are provided, but the protection scope of the present invention is not limited to the following the described embodiment.

Example:

The project example is the comprehensive reconstruction (phase I) project of a certain area in Shanghai. The east side of the construction site of the project is the Huangpu River flood control wall, which was built in the 1970s and was heightened and reinforced in the early 1990s. The traffic around the construction site is heavy, and there are underground pipelines distributed. The new temporary flood control wall has effectively isolated the construction area from pipelines and roads.

The foundation pit engineering of buildings in the land area of this project is divided into 4 construction areas A, B, C and D. The enclosure structure adopts an 800mm thick underground diaphragm wall with a depth of 27m to 28m, and three horizontal reinforced concrete supports are used in the pit. The excavation method of the foundation pit is conventional construction. The excavation depth of the foundation pit is 13.5m, and the total extension of the foundation pit is 1200m.

In order to check the groove construction quality of the underground diaphragm wall, the wall mud pressure test device shown in Figure 1 is used in the groove construction of this project, including: protective collar 1, elastic screw 2, hook 3, pressure sensor 4, data Transfer wire 5, measuring rope 6, lifting frame 7 and data acquisition instrument 8. The pressure sensor 4 is set in the protective collar 1, and the protective collar 1 is provided with a slot, and the data transmission wire 5 of the pressure sensor 1 is drawn out from the slot, and connected to the data acquisition instrument 8, and the upper part of the protective collar 1 is connected to the There is a hook, and the lifting frame 7 is mounted on the continuous wall groove section, and a wheel is installed on the lifting frame 7, and the measuring rope 6 lower ends are bound with the hook 3, and the upper end is fixed and coiled on the wheel of the lifting frame 7.

The specific test method steps of the present embodiment are as follows:

In the first step, the protective collar 1 is prepared before the construction of the continuous wall groove. Three elastic screws 2 are installed on the outer side of the collar. The upper end of the collar has a slot and is connected with a hook 3 .

In the second step, loosen the elastic screw 2, install the pressure sensor 4 in the collar 1, and tighten the screw 2 to fix the pressure sensor 4.

In the third step, the data transmission wire 5 of the pressure sensor 4 is drawn out from the slot hole of the collar 1 , together with the measuring rope 6 bound on the hook 3 , and connected to the metal lifting frame 7 .

In the fourth step, after the excavation construction of the groove forming machine is completed, the pressure sensor 4 is slowly slid into the groove section from the mud liquid level through the pulley of the lifting frame 7, and the data acquisition instrument 8 is used on the ground at a vertical interval of 1.0m. The pressure is measured and read until the pressure sensor slides to the bottom of the groove section.

Step 5: Starting from the bottom of the tank section, slowly lift the pressure sensor 4 upwards, and repeat the pressure measurement at every vertical interval of 1.0m until the pressure sensor 4 reaches the mud level.

The sixth step is to average the mud pressure results measured by sliding down and lifting up at the same depth, draw the scattered point data between the depth and the mud pressure, and fit the scattered point data to obtain the different depths in the groove section. mud pressure.

In the first step, the inner diameter of the protective collar 1 is 12.3 cm, the thickness is 2.5 cm, and the inner diameter of 8 mm is larger than that of the pressure sensor 4 to ensure that the pressure sensor 4 can be smoothly inserted into the collar. There are three elastic screws 2 with a diameter of 4mm on the outside with a diameter of 8mm, which can fix the pressure sensor 4 . The upper part with a diameter of 8 mm has a slot with a diameter of 8 mm, and the inner diameter of the slot is larger than the diameter of the pressure sensor data transmission wire 5 .

In the second step, the pressure sensor has a diameter of 12cm, a thickness of 2.5cm, and a range of 1.5 times the estimated maximum mud pressure. The pressure sensor is connected with a data transmission wire that can be measured and read by a data acquisition instrument, and the wire is a double-core measuring cable with a diameter of 6mm. The wire is led out from the slot hole of the collar to the ground, so that the tester can read the data on the ground.

In the third step, there is a scale on the measuring rope to ensure that the depth of the pressure sensor in the groove section can be read. The lower end of the measuring rope is bound to the hook of the collar to prevent the collar and the pressure sensor from slipping off.

In the fourth step and the fifth step, the lifting frame has four fulcrums, which are respectively mounted on both sides of the continuous wall groove section. The upper rollers of the lifting frame can control the depth of the pressure sensor, the speed of the pressure sensor sliding and lifting.

In the fourth and fifth steps, the pressure sensor needs to ensure that the depth position of the pressure sensor is the same during the downward and upward readings, so as to compare the reading data.

In the sixth step, the mud pressure results measured at the same depth are averaged to reduce the reading error caused by one reading.

The foundation pit project used the above method to carry out the mud pressure test of three underground continuous groove sections (D15, D31 and DQC2b), and the mud pressure curves measured by the three groove sections are shown in Figure 2, Figure 3 and Figure 4 . The test results well reflect the increasing relationship of mud pressure with depth. In order to facilitate the comparison and verification of the test results, the conventional mud hydrometer method was used in the three tank sections to take samples at different depths and measure the mud specific gravity, which was then converted into mud pressure. The converted mud pressure is also drawn in Fig. 2, Figure 3 and Figure 4. The mud pressure after conversion is lower than the mud pressure obtained by the test of the present invention, but the relative error is within 0.83%, indicating that the test accuracy of the embodiment of the present invention meets the engineering requirements. Due to the tightness of the mud barrel in the mud sampling process, the hydrometer method has the phenomenon of mud leakage and mud mixing, which leads to the mud pressure measured by this method being less than the mud pressure measured by the present invention.

In the actual test process, it only takes 10 minutes to perform a mud pressure test (sliding down and lifting up), which has little impact on the construction progress of the subsequent concrete pouring of the diaphragm wall. The conventional hydrometer method takes 5 minutes to sample and test each depth point. In the embodiment, the sampling tests of four depth positions of -5m, -10m, -15m and -20m were respectively carried out in each groove section. , the total time needs 25 minutes, which is 2.5 times of the required time of the inventive method. But the number of data points that conventional hydrometer method can obtain in 2.5 times of time is only about 1/6 of the inventive method, illustrates that the testing efficiency of the inventive method is obviously better than conventional hydrometer method.

Claims (10)

1, the method for testing of slurry coat method pressure in a kind of continuous wall trench underground construction is characterized in that, may further comprise the steps:

The first step is prepared the metal coating collar that a upper end has slotted eye, the graduated lining rope of binding strap on the hook of the collar;

In second step, the screw in the collar outside is unscrewed the pressure sensor of packing into, tighten the screws fixation pressure sensor in the collar;

The 3rd step, the data of pressure sensor are transmitted lead from the slotted eye of the collar, draw, the lining rope of colligation is drawn on the collar, is connected on the crane that is set up in ground;

The 4th step, by crane with pressure sensor in the sliding groove inlet section of mud liquid level, carry out the survey of pressure sensor and read every setting vertical spacing, slide to groove section bottom until pressure sensor;

The 5th goes on foot, and from the beginning of groove section bottom, pressure sensor is upwards promoted, and the survey that repeats pressure sensor every the vertical spacing of setting is read, and is promoted to the mud liquid level until pressure sensor and finishes;

In the 6th step, the mud pressure result that same depth is measured averages, and draws the diffusing point data of the degree of depth and mud pressure relation, and the point data of will loosing is carried out match, and the mud pressure that gets each degree of depth in the groove section distributes.

2, the method for testing of slurry coat method pressure in the continuous wall trench underground construction according to claim 1, it is characterized in that, in the 4th step and the 5th step, pressure sensor is surveyed in the data that glide and promote and is read, and glides to surveying that to read when promoting survey and read the depth location of pressure sensor identical.

3; the testing arrangement of slurry coat method pressure in a kind of continuous wall trench underground construction; it is characterized in that; comprise jacking system and test macro; described jacking system comprises the protection collar; lining rope; crane; described test macro comprises pressure sensor; data are transmitted lead; data collecting instrument; wherein: pressure sensor is arranged in the protection collar; the protection collar is provided with slotted eye; the data of pressure sensor are transmitted lead and are drawn from this slotted eye; and be connected to data collecting instrument; there is parbuckle screw in the protection collar outside, is used for fixing pressure sensor, and protection collar top is connected with hook; the crane frame is on continuous wall groove segment; wheel is installed on the crane, lining rope lower end and hook binding, the upper end is fixed and is coiled on the wheel of crane.

4, the testing arrangement of slurry coat method pressure in the continuous wall trench underground construction according to claim 3 is characterized in that, the described protection collar, and its internal diameter is greater than the pressure sensor diameter.

5, the testing arrangement of slurry coat method pressure in the continuous wall trench underground construction according to claim 3 is characterized in that, the slotted eye on described protection collar top, and its internal diameter transmits diameter of wire greater than pressure sensor data.

6, according to the testing arrangement of slurry coat method pressure in claim 3 or the 5 described continuous wall trench underground constructions, it is characterized in that it is that twin-core is measured cable that described data are transmitted lead, data are transmitted lead and are extended to ground from pressure sensor.

7, the testing arrangement of slurry coat method pressure in the continuous wall trench underground construction according to claim 3 is characterized in that described lining rope has scale.

8, the testing arrangement of slurry coat method pressure in the continuous wall trench underground construction according to claim 3 is characterized in that described crane has four fulcrums, and frame is in the continuous wall groove segment both sides respectively.

9, the testing arrangement of slurry coat method pressure in the continuous wall trench underground construction according to claim 3 is characterized in that described pressure sensor is the type vibration wire pressure gauge.

According to the testing arrangement of slurry coat method pressure in claim 3 or the construction of 9 described continuous wall trench undergrounds, it is characterized in that 10, described pressure sensor, its range are to estimate 1.5 times of maximum mud pressure.

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