CN115478552A - A kind of caisson sinking construction method under hard rock geological conditions - Google Patents

Abstract

The invention discloses a caisson sinking construction method under the condition of hard rock geological conditions. S1: Level the ground site so that the site meets the construction requirements of a rotary drilling rig. S2: Position the inner and outer walls of the caisson according to the design drawings, and adopt a plum-shaped design Layout and mark the lead holes, step S3: use the rotary drilling drill to drill holes using the jump hole method, the drilling sequence follows the outer circle first and then the inner circle, step S4: immediately backfill with gravel and slag after each hole is completed , Prevent hole collapse or perforation, and reduce the impact on subsequent drilling construction. S5: Subsequent caisson fabrication and construction shall be carried out in the way of excavation and sinking after all boreholes are backfilled. The invention uses a rotary drilling rig to break the hard rock structure before the construction of the caisson, reduces the difficulty of subsequent caisson excavation and sinking, accelerates the sinking speed of the caisson, facilitates the control of the amount of excavated soil under the edge angle, and reduces the risk of inclination of the caisson probability, greatly shortening the construction period of caissons in hard rock formations.

Description

A kind of caisson sinking construction method under hard rock geological conditions

technical field

The invention belongs to the technical field of municipal engineering construction, and in particular relates to a caisson sinking construction method under hard rock geological conditions.

Background technique

The sinking construction of the caisson is mainly to remove the soil uniformly from the caisson by mechanical or manual methods, weaken the frontal resistance of the base soil to the blade foot and the frictional resistance between the caisson wall and the soil, so that the caisson relies on its own gravity to overcome the above-mentioned resistance. sink.

When the caisson construction area is a hard rock formation, in the past, the method of crushing rock by gun machine was used for caisson construction. However, due to the hardness of the rock formation, the efficiency of rock crushing by gun machine is low, and it is difficult to evenly remove the rock at the bottom and edge of the well. As a result, the caisson well wall and lower side are easily stuck by hard rocks, or sideways phenomenon occurs, seriously affecting the construction period of the caisson and causing great obstacles to the advancement of subsequent pipe jacking construction.

Contents of the invention

In order to overcome the problem of difficult sinking of caissons in rock formations in the prior art, the present invention provides a construction method for subsidence of caissons in hard rock geological regions, which reduces the difficulty of subsequent caisson construction and the difficulty of caisson inclination. probability, it is convenient for the subsequent caisson construction to evenly excavate the rock in the well hole, which is conducive to the rapid and uniform subsidence of the caisson, and solves the above technical problems.

A caisson sinking construction method under hard rock geological conditions, the construction method includes the following construction steps:

S1: Lead hole preparation, encircling the site before construction, using measuring equipment to locate and mark the location of the caisson, using a breaking hammer to chisel out the concrete on the original ground, consigning the equipment into the site, and using a rotary drilling rig for the leading hole equipment, The drill bit is a rock-breaking drill bit with a diameter of 1m;

S2: Design and measurement, determine the specific location according to the plane design drawing of the caisson, plan multiple guide holes referring to the specific location of the caisson, and carry out measurement and setting out according to the design drawing. Hole construction scope;

S3: Rotary drilling construction, use the rotary drilling rig to lead the hole, and the method of leading the hole is to use the jump hole method for construction. The construction sequence is the outer ring and then the inner ring. In order to prevent insufficient rock breaking depth, the design depth of drilling is generally 0.5m deeper than the design elevation of the bottom of the caisson;

S4: Drilling and backfilling, every drilled hole that has completed the lead hole needs to be backfilled with gravel, and then start the construction of the next drilling hole, and use the method of backfilling one by one;

S5: Fabrication of caisson and excavation and sinking. After the introduction hole and backfilling are completed, the follow-up construction will be carried out according to the conventional caisson construction plan.

In the above-mentioned construction method of caisson sinking under hard rock geological conditions, the center of the caisson in the step S2 coincides with the central leading hole, and six boreholes are arranged around the central hole at intervals of 0.4m-0.5m to surround them evenly, and the outer ring is 18 The boreholes are evenly distributed, and the distance between the two circles of boreholes is about 0.4m-0.5m. The outer wall of the caisson is designed to coincide with the circle formed by the center of the outermost circle of boreholes.

In the above-mentioned construction method of caisson sinking under hard rock geological conditions, the drilling in the step S3 is carried out using a rotary drilling rig, and is carried out according to the design pile number, and the drilling sequence is carried out one by one from the outer circle to the inner circle, and each circle Drilling is carried out using the jump hole method.

In the above-mentioned caisson sinking construction method under hard rock geological conditions, the drilling method in the step S4 adopts the hole-jumping method, and the construction is continued every other drilling hole after the first drilling hole is completed, and each drilling hole is completed immediately. Backfill with crushed rock.

In the above-mentioned caisson sinking construction method under hard rock geological conditions, the sinking-assisting method of breaking the rock formation structure in advance by the rotary drilling and pilot hole in the step S5 is used before the caisson construction.

Generally speaking, compared with the prior art, the above technical solutions conceived by the present invention can achieve the following beneficial effects:

1. A construction method for caisson sinking under hard rock geological conditions of the present invention. The caisson sinking construction method under hard rock geological conditions can improve the construction efficiency of caissons in hard rock formations. Before the caisson foundation pit is made, a rotary drilling rig is used to carry out The introduction hole can break the hard rock structure in advance, reduce the difficulty of rock crushing by the long-arm cannon, speed up the excavation speed of caisson sinking in the later stage, and greatly shorten the construction period of caisson in hard rock formation

2. The boreholes of the rotary drilling drill described in the present invention are symmetrically arranged in a quincunx shape, and the position of the edge angle of the caisson is designed to be set between two circles of boreholes, which can effectively reduce the number of deviation corrections of the caisson when the caisson is excavated and sinks, and further The construction period is saved, and the method of backfilling each drill hole one by one reduces the influence between adjacent drill holes, provides a stable support plane, and ensures the construction environment of the subsequent caisson.

Description of drawings

Below in conjunction with accompanying drawing, specific embodiment of the present invention is described in further detail, wherein:

Fig. 1 is the construction process flowchart of caisson sinking construction method under a kind of hard rock geological situation of the present invention;

Fig. 2 is the plane design drawing that the present invention carries out rotary drilling and drilling pilot hole;

Fig. 3 is a schematic diagram of the drilling sequence of the present invention;

In the figure: 1- the construction range of the lead hole, 2- the outer wall of the caisson, 3- the inner wall of the caisson, and 4- the drilling.

detailed description

The invention mainly solves the problem of slow sinking of caissons under hard rock geological conditions, and provides an efficient caisson construction method.

Application of a caisson sinking construction method under hard rock geological conditions in a pipe jacking project. The strata for caisson construction from top to bottom are: gravel silty soil, strongly weathered glutenite, and moderately weathered glutenite; the design It is required that the depth of the pipe jacking working well is 13.5 meters, the size of the caisson is: inner diameter 7 meters, outer diameter 8.5 meters, wall thickness 0.75m; the caisson is made by cast-in-place method.

In this embodiment, the process flow of the rapid subsidence construction method of the pipe jacking well under the hard rock geological conditions is shown in Figure 1, which specifically includes the following steps:

Step 1: Construction preparation. Before construction, by enclosing the site, measuring and setting out the caisson structure, confirming the location of the caisson, and leveling the enclosing site to meet the design ground elevation and meet the requirements of the rotary drilling rig construction site.

Step 2: Positioning of the lead hole. According to the caisson design drawing, determine the caisson center stake number, mark the range of the caisson according to the inner and outer diameters of the caisson, spread out from the center stake number, and determine the lead hole stake number. The lead hole is plum blossom The design of the caisson bezel should be between the two boreholes as much as possible, and the range of the drilled holes should not only cover the range of the caisson, but also ensure the minimum number of drilled holes.

The specific drilling plan distribution diagram is shown in Figure 2. The diameter of the rotary drilling bit is 1m, and the distance between adjacent holes is between 0.4-0.5m. It can be seen from Figure 2 that the center is a single drilling hole, and the inner ring is 6 drilling holes. The holes are evenly arranged in a ring, with a distance of 0.45m from the central hole; the secondary inner ring is uniformly arranged with 12 drill holes, and the distance from the inner ring is 0.4m; The spacing is 0.4m. It can be seen from Figure 2 that the caisson edge position is set between the outer ring and the secondary inner ring.

Step 3: Rotary drilling construction, use the rotary drilling rig to carry out the construction of the lead hole, the construction sequence is shown in Figure 3, and the sequence is: according to the drilling construction from the outside to the inside, the drilling sequence of each circle depends on the site conditions.

In order to prevent insufficient hole depth, the design depth of the drill hole is 0.5m deeper than the design elevation of the caisson bottom, and the drill bit of the rotary drilling rig adopts a rock-breaking drill bit with a diameter of 1m.

Step 4: Drilling and backfilling. Each drilled hole that has completed the lead hole needs to be backfilled with gravel, and then start the construction of the next drilled hole. The method of backfilling one by one can avoid the use of empty holes in the drilled hole. The support causes the collapse of the hole or the problem of stringing holes during the construction of adjacent drilling holes. On the one hand, it can also provide a stable support surface for the subsequent caisson edge formwork pouring.

Step five: caisson fabrication and excavation sinking, caisson fabrication and excavation sinking. After the introduction hole and backfilling are completed, the follow-up construction will be carried out according to the conventional caisson construction plan.

The sedimentation aid method of breaking the rock structure in advance by rotary drilling and drilling the pilot hole is used before caisson construction. Since all the drill holes are backfilled with crushed stones in step 4, the subsequent foundation pit excavation, cushion treatment and The main role of rotary drilling and pilot holes is to reduce the difficulty of rock breaking and excavation operations in the subsequent caisson sinking process. The follow-up construction sequence is: foundation pit excavation→cushion layer construction→edge formwork pouring→formwork removal and maintenance→caisson sinking and bottom sealing.

It can be seen from the examples that the construction period of the caisson is 9 days by using rotary drilling and drilling the pilot hole, the construction period of the caisson sinking is 22 days, and the total construction period is 31 days, and because the drilling holes are evenly distributed, the sinking of the caisson is relatively smooth, and there is almost no need for construction. Corrective processing. Under the same geological conditions, the construction of adjacent working wells using long-arm cannons and long-arm excavators took 69 days in total, and the bottom of the caisson was stressed due to the inhomogeneity of the rock formation during the excavation process. The unevenness caused the caisson to tilt, and several deviation corrections were performed. Comparing the construction period of adjacent working wells under the same geological conditions, it can be seen that the present invention solves the problems of difficult excavation in hard rock formations and prone to inclination, and the construction period of caissons is reduced by 50%.

It is easy for those skilled in the art to understand that the above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present invention, etc., All should be included within the protection scope of the present invention.

Claims (5)

1. a caisson sinking construction method under a hard rock geological situation, is characterized in that, the construction method comprises the following construction steps: S1: Lead hole preparation, encircling the site before construction, using measuring equipment to locate and mark the location of the caisson, using a breaking hammer to chisel out the concrete on the original ground, consigning the equipment into the site, and using a rotary drilling rig for the leading hole equipment, The drill bit is a rock-breaking drill bit with a diameter of 1m; S2: Design and measurement, determine the specific location according to the plane design drawing of the caisson, plan multiple guide holes referring to the specific location of the caisson, and carry out measurement and setting out according to the design drawing. Hole construction scope (1); S3: Rotary drilling construction, use the rotary drilling rig to guide the hole, the drilling method adopts the jump hole method, and the construction sequence is the outer ring and then the inner ring. In order to prevent the rock breaking depth from being insufficient, the designed depth of the drilled hole is generally lower than the design at the bottom of the caisson. Elevation depth 0.5m; S4: Drilling backfilling, each drill hole (4) that has completed the lead hole needs to be backfilled with gravel, and then start the next drilling construction, and use the method of backfilling one by one; S5: After caisson fabrication, excavation and sinking, leading holes and backfilling are completed, follow-up construction shall be carried out according to the conventional caisson construction plan. 2. The caisson sinking construction method under a hard rock geological condition according to claim 1, characterized in that the center of the caisson in the step S2 coincides with the central leading hole, and the center hole is set at an interval of 0.4-0.5m The six boreholes are evenly surrounded, and the 18 boreholes in the outer circle are evenly distributed. The distance between the two circles of boreholes is about 0.4-0.5m. The circle formed by the outer wall of the caisson (2) and the center of the outermost borehole coincide. 3. The caisson sinking construction method under a kind of hard rock geological condition according to claim 1, characterized in that, the drilling in the step S3 adopts a rotary drilling rig for construction, and is carried out according to the design pile number, and the drilling sequence Carry out one by one from the outer ring to the inner ring, and each ring is drilled by the jump hole method. 4. The caisson sinking construction method under a kind of hard rock geological condition according to claim 1 is characterized in that, the drilling method in the step S4 adopts the method of skipping holes, and after the first drilling is completed, every other drilling Construction of the holes continued, backfilling with crushed stone immediately after each hole was drilled. 5. The sinking construction method of the caisson under a kind of hard rock geological condition according to claim 1, characterized in that, the method of assisting the sinking of the rock structure in advance by rotary drilling in the step S5 is in the caisson Use before construction.

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