Method for blocking large gushing water in rock fracture zone of foundation pit

Abstract

The present invention relates to a method for blocking large gushing water in a rock fracture zone of a foundation pit. The method comprises: leveling a site of a water gushing point area of a fracture zone, and measuring attitude parameters of the fracture zone; mounting a water collection hood in a foundation pit, and welding a steel drainage pipe to the top portion of the water collection hood; determining an arrangement range and arrangement mode of grouting drill holes; building a counter-pressure soil platform around the water collection hood; discharging gushing water into the foundation pit by means of the steel drainage pipe, and controlling the difference of water levels inside and outside the foundation pit; constructing grouting drill holes on the top surface of the counter-pressure soil platform; performing grouting blocking on water gushing points; and when the water gushing points are completely and successfully blocked and there is no water gushing, stopping grouting, and then pumping out accumulated water in the bottom portion of the foundation pit, and removing the counter-pressure soil platform. The present invention has the beneficial effects of avoiding blind backfilling of counter-pressure soil, reducing the earthwork volume of the counter-pressure soil, the number of drill holes and the grouting workload, lowering the emergency rescue cost, controlling the cost, achieving a stable overall structure, and avoiding the seepage of contact surfaces between counter-pressure soil platforms and rocks at the pit bottoms, thus achieving a good water blocking effect and a high success rate.

Description

Foundation rock fissure zone large gushing water plugging method TECHNICAL FIELD

[0001] The present application relates to the field of building, civil and traffic engineering, in particular to a foundation rock fissure zone large gushing water plugging method. BACKGROUND

[0002] When the foundation pit excavation depth is large, and the bedrock depth is shallow, the bedrock fissure is developed, especially when the bottom of the pit exists a hidden water-bearing fissure zone, it is often a type of confined water, rich in water, large water pressure, and when the foundation pit excavation encounters the water-bearing fissure zone, it will definitely gush, because the gushing water is large, the foundation pit is quickly submerged, causing the equipment to be soaked, which seriously threatens the safety of the foundation pit and the surrounding environment, especially the workers. After the gushing occurs, the excavation of earthwork and support work must be stopped immediately, the workers in the pit are evacuated, and a large flow water pump is added to drain the accumulated water in the pit. Strong drainage cannot solve the fundamental problem of gushing, and has a large impact on the surrounding environment, causing a lot of loss. Only by plugging the gushing water can safety be ensured. For the problem of large flow gushing water in the rock fissure zone at the bottom of the pit, there is no way in many cases, and the only way is to backfill the foundation pit and then fully grout the bottom of the pit. This method is high in cost and time-consuming, and if the gushing channel cannot be cut off, there is still a risk of gushing when excavating again.

[0003] Patent with publication number CN117661615A discloses a plugging method for sudden gushing water at the bottom of a foundation pit, a drainage pipe is arranged at the gushing point, reverse pressure concrete is poured, a concrete operation platform is arranged above the drainage pipe, a row of water retaining walls are arranged on the platform, the gushing water is introduced into the operation platform and pumped away, the position of the gushing point is determined, and the gushing point is treated by drilling and grouting outside the water stop curtain. The method uses concrete reverse pressure when the gushing water at the bottom of the foundation pit has a large flow rate. Engineering emergency rescue practice shows that the contact interface between the drainage pipe and the rock-soil at the bottom of the foundation pit cannot be completely closed, and the seepage will wash away the cement slurry before the concrete sets. Moreover, no method is provided for determining the gushing channel. Patent with publication number CN206667278U discloses a construction structure for treating gushing water from karst fissures. The drainage cavity is formed by building a maintenance structure at the gushing outlet and then pouring concrete to seal it. The same problem exists as in the above patent. Patent with publication number CN110080230A discloses a structure for treating gushing water at the bottom of a foundation pit and a construction method thereof. A cofferdam is arranged around the gushing point, and the cofferdam is formed by surrounding multiple sandbags. The same problem exists as in the above patents. In addition, the grouting and plugging of the gushing point at the bottom of the foundation through the diversion pipe will not be successful due to the high water pressure and flow in the diversion pipe. Patent with publication number CN105780793B discloses an emergency treatment method for sudden gushing of high-pressure water stratum at a foundation pit. A steel casing is arranged at the gushing point, and a small amount of sandbags are filled around the bottom of the steel casing on the outside to form a reverse pressure platform. The same problem exists as in the above patents, and it is unclear how to arrange the grouting holes and drill how deep. Based on the above existing documents, it can be known that there are common unsolved problems in the prior art, including: (1) the interface between the water collector and the rock-soil is not sealed, and a seepage surface is formed at the bottom of the reverse pressure platform; (2) no measurement and calculation method is provided for determining the strike, tendency and inclination of the rock fissure zone; (3) no method is provided for determining the planar arrangement of the grouting holes and the drilling depth; and (4) the grouting holes are arranged at the bottom of the pit, the grouting path is short, which is not conducive to the solidification of the slurry, and affects the grouting effect. SUMMARY

[0004] The purpose of the present application is to overcome the shortcomings of the prior art and provide a method for plugging large gushing water in a rock fissure zone at a foundation pit, which can avoid the blindness of backfilling reverse pressure soil, reduce the amount of backfilling reverse pressure soil, the number of drill holes and the amount of grouting work, reduce the cost of emergency rescue, control the cost, and the overall structure is stable, which can avoid the seepage between the reverse pressure soil bottom and the rock contact surface, has good water plugging effect and high success rate.

[0005] The purpose of the present application is achieved by the following technical solutions:

[0006] A method for plugging large gushing water in a rock fissure zone at a foundation pit, comprising the following steps:

[0007] S1, leveling the site of the gushing point area of the fissure zone and determining the occurrence parameters of the fissure zone, the occurrence parameters of the fissure zone including length, width, strike, tendency and inclination.

[0008] S2, installing a water collecting cover in the foundation pit to cover the fractured zone and to concentrate the scattered water gushing points in the fractured zone in the water collecting cover, and welding a steel drain pipe on the top of the water collecting cover.

[0009] S3, determining the arrangement range and arrangement mode of the grouting drill holes according to the occurrence of the fractured zone.

[0010] S4, piling up a counter-pressure earth platform around the water collecting cover, the top surface of the counter-pressure earth platform covering the arrangement range of the grouting drill holes, and the height of the counter-pressure earth platform being at least 1m higher than the designed water level in the foundation pit.

[0011] S5, discharging the water gushing into the foundation pit through the steel drain pipe, and controlling the water level difference between inside and outside of the foundation pit to be within 3m, and discharging the water accumulated in the foundation pit above the designed water level through a water pump.

[0012] S6, constructing the grouting drill holes on the top surface of the counter-pressure earth platform according to the arrangement range and arrangement mode of the grouting drill holes, and the grouting drill holes should penetrate the fractured zone and enter the intact rock by not less than 1m.

[0013] S7, plugging the water gushing points by grouting, and the grouting sequence being converging from the periphery of the fractured zone to the center of the water gushing points.

[0014] S8, when the water gushing points are completely plugged successfully and there is no water gushing, stopping the grouting, then pumping out the water accumulated in the bottom of the foundation pit and removing the counter-pressure earth platform.

[0015] Further, the trend of the fractured zone is determined by a total station, when determining, the north direction is determined by a compass, a straight line with length a is drawn along the north direction at one end of the fractured zone, and a straight line with length b is drawn perpendicular to the north direction at the other end of the fractured zone, then the trend angle δ of the fractured zone is calculated according to the formula .

[0016] Further, when determining the tendency and dip angle of the fractured zone, the tendency is preliminarily determined by excavating the shallow part of the fractured zone, a profile line is made perpendicular to the trend of the fractured zone, and three drill holes m1, m2 and m3 are arranged on the profile line according to intervals a1, a2, respectively, the horizontal angles of the upper boundary line of the fractured zone are α1 and α2, respectively, the horizontal angles of the lower boundary line of the fractured zone are β1 and β2, respectively, the distance between the drill hole m1 and the drill hole m2 on the upper boundary line of the fractured zone is t1, the distance between the drill hole m2 and the drill hole m3 on the upper boundary line of the fractured zone is t2, the distance between the drill hole m1 and the drill hole m2 on the lower boundary line of the fractured zone is t3, and the distance between the drill hole m2 and the drill hole m3 on the lower boundary line of the fractured zone is t4, then α1, α2, β1 and β2 are sequentially solved according to the formula , and the average value of α1 and α2 is taken as the dip angle of the upper boundary line of the fractured zone, and the average value of β1 and β2 is taken as the dip angle of the lower boundary line of the fractured zone.

[0017] Further, the water collecting cover is cut and welded from steel plate into a frustum shape, and the size of the water collecting cover is determined according to the occurrence of the fissure zone, the area of the water gushing point and the water gushing amount.

[0018] Further, when the water collecting cover is installed, an anchor steel plate is processed on the bottom periphery of the water collecting cover, a rubber strip is arranged at the contact surface between the bottom edge of the water collecting cover and the rock, and the anchor steel plate is fixed on the rock through the expansion bolts, so that the anchor steel plate presses the rubber strip.

[0019] Further, the diameter and the number of the steel drainage pipe are determined according to the water gushing amount, the height of the steel drainage pipe is 1m-2m, and the plastic drainage pipe is connected to the steel drainage pipe through a joint pipe and extended to the outside of the counter-pressure earth platform.

[0020] Further, when the arrangement range and the arrangement mode of the grouting drill hole are determined, the grouting drill hole is arranged in parallel to the strike of the fissure zone with the water gushing point as the center, one row of grouting drill holes is arranged on each side of the fissure zone, the hole spacing of each row of grouting drill holes is 0.5m-2m, the drilling direction of the grouting drill hole drilled to the fissure zone is the dip direction of the fissure zone, and no less than three rows of grouting drill holes are arranged in the dip direction of the fissure zone in a plum blossom shape from outside to inside.

[0021] Further, the shape of the counter-pressure earth platform is determined according to the number of the water gushing points, the single water gushing point adopts a circular frustum shape, and the multiple water gushing points adopt a rectangular frustum shape.

[0022] Further, the core of the counter-pressure earth platform is backfilled with cohesive soil, the periphery of the counter-pressure earth platform is filled with medium-coarse sand or gravel soil, and the slope of the counter-pressure earth platform is protected through the stacking of sand bags or block stones.

[0023] Further, when the grouting plugging is performed, the grouting is immediately performed through the double-pipe double-liquid grouting method after the grouting drill hole is drilled, the flow time of the slurry from the hole bottom outflow port to the initial setting in the fissure zone is not less than 30s, and the single-hole grouting pressure is not greater than 5.0MPa.

[0024] Compared with the prior art, the present application has the following beneficial effects:

[0025] 1. The present application accurately determines the occurrence parameters of the fissure zone, determines the arrangement range and the arrangement mode of the grouting drill hole according to the parameters, determines the coverage range and the height of the counter-pressure earth platform, is beneficial to avoiding the blindness of the backfilling of the counter-pressure earth, reduces the backfilling earthwork amount, the subsequent drilling number and the grouting workload, makes the drilling and grouting work have a clear direction, reduces the rescue cost, controls the cost, and is very effective for the fissure zone water gushing plugging of the rock at the bottom of the foundation pit.

[0026] 2、The present application concentrates the dispersed free-flowing gushing water through the water collecting cover, and drains it to the outside of the counter-pressure soil platform through the drain pipe, and the rubber strip is placed under the bottom edge of the water collecting cover, and the water collecting cover is anchored with the rock through the expansion bolt, so that the gushing water is collected in the water collecting cover, and no seepage occurs, thereby concentrating the gushing water for discharge, which is beneficial to ensuring the stability of the counter-pressure soil platform.

[0027] 3、The present application discharges the gushing water into the foundation pit to maintain a certain water level, and controls the water level difference between the inside and outside of the foundation pit to be within 3.0m, thereby reducing the water pressure and flow rate of the gushing water, and prolonging the grouting channel through the height of the counter-pressure soil platform, so that the slurry injected into the fracture zone is not washed away by the high-speed water flow, which is beneficial to successful water plugging.

[0028] 4、The present application sets the counter-pressure soil platform, which can be directly used as an operation platform for drilling and grouting construction under the condition that the foundation pit is full of water, which is convenient for drilling and grouting construction, and can also increase the path of slurry flow, which is beneficial to rapid solidification of the slurry after injection into the fracture zone, thereby reducing the risk of water plugging failure. BRIEF DESCRIPTION OF DRAWINGS

[0029] Fig. 1 is a plan layout schematic diagram of a gushing water point of a foundation pit rock fracture zone in the present application;

[0030] Fig. 2 is a whole structure plan schematic diagram of the present application;

[0031] Fig. 3 is a whole structure cross-sectional schematic diagram of the present application;

[0032] Fig. 4 is a cross-sectional schematic diagram of a grouting drill hole in the present application;

[0033] Fig. 5 is a structure schematic diagram of a water collecting cover in the present application;

[0034] Fig. 6 is a grouting schematic diagram when grouting plugging in the present application;

[0035] Fig. 7 is a fracture zone trend determination schematic diagram in the present application;

[0036] Fig. 8 is a fracture zone inclination and dip angle determination schematic diagram in the present application.

[0037] In the drawings: 101, underground continuous wall; 102, excavation face; 103, foundation pit bottom; 104, fracture zone; 105, gushing water point; 106, rock fracture; 2, water collecting cover; 201, anchoring steel plate; 202, rubber strip; 203, expansion bolt; 3, steel drain pipe; 301, plastic drain pipe; 302, joint pipe; 401, counter-pressure soil platform; 402, block stone; 5, grouting drill hole; 501, grouting body. DETAILED DESCRIPTION

[0038] The application will be further described below with reference to the drawings, but the scope of protection of the application is not limited to the following description.

[0039] As shown in Figures 1-8, in order to solve the problem of water gushing in the rock fissure zone of a foundation pit, the application studies a large water gushing plugging method for the rock fissure zone of a foundation pit and a water plugging system corresponding to the method. The water gushing plugging mainly adopts the way of drilling and grouting to plug the water gushing points 105 in the fissure zone 104. The water plugging system specifically consists of a drainage system, a counter-pressure earth platform 401 and a grouting system.

[0040] As shown in Figure 4, the drainage system includes a water collecting cover 2, a steel drainage pipe 3 and a water pump. The water collecting cover 2 is cut and welded from a steel plate into a frustum shape. The water collecting cover 2 is installed at the fissure zone 104 to cover the fissure zone 104 and concentrate the dispersed water gushing together. The size of the water collecting cover 2 is determined according to the occurrence of the fissure zone 104, the area of the water gushing points 105 and the water gushing amount. When the length of the fissure zone is large, multiple water collecting covers 2 can be spliced together for use. The steel drainage pipe 3 is welded at the top of the water collecting cover 2 to drain the water gushing in the water collecting cover 2 to the foundation pit. The water pump is used for pumping water.

[0041] The counter-pressure earth platform 401 is operated by a hook machine and piled up. The core backfill of the counter-pressure earth platform 401 is cohesive soil. The surrounding of the counter-pressure earth platform 401 is filled with medium-coarse sand or gravel soil as filter material. The slope of the counter-pressure earth platform 401 is protected by piling up sand bags or block stones 402. The grouting drilling hole 5 before plugging is directly constructed on the counter-pressure earth platform by a drilling machine with a drill bit diameter of 101 mm. The arrangement range of the grouting drilling hole 5 is determined according to the occurrence of the fissure zone. At the same time, the arrangement mode of the grouting drilling hole 5 is determined before drilling. The grouting drilling hole 5 is drilled downward to penetrate the fissure zone. Through the setting of the counter-pressure earth platform 401, the drilling and grouting construction can be facilitated in the case that the foundation pit is full of water. At the same time, the path of the slurry flow can be increased, which is beneficial to the rapid solidification of the slurry after being injected into the fissure zone and reduces the risk of water plugging failure.

[0042] The grouting system consists of the grouting drilling hole 5 passing through the fissure zone, the double-hole grouting pipe, the cement slurry, the water glass, the slurry stirring barrel and the grouting pump. The cement slurry and the water glass are mixed and stirred uniformly in the slurry stirring barrel. The double-hole grouting pipe is inserted into the grouting drilling hole 5. Then the grouting pump is used to inject the slurry into the fissure zone to plug the water gushing points 105.

[0043] Based on the overall structure of the above water plugging system, the large water gushing plugging method for the rock fissure zone of a foundation pit adopted by the application includes the following steps:

[0044] S1, level the site of the water gushing point 105 area of the fissure zone 104 and measure the occurrence parameters of the fissure zone, wherein the occurrence parameters of the fissure zone 104 include length, width, strike, trend and dip angle.

[0045] Specifically, as shown in FIG. 1, the foundation pit is excavated within the range enclosed by the underground continuous wall 101, when the foundation pit excavation face 102 encounters the fissure zone 104, the groundwater in the fissure zone 104 gushes out from the gushing point 105, when the gushing point 105 is found, the broken rock and muck near the gushing point 105 are immediately removed, the uneven rock is removed, and the surface of the gushing point 105 area is leveled; the length and width of the fissure zone 104 are directly measured using a measuring scale.

[0046] The trend of the fissure zone 104 is determined by a total station instrument, as shown in FIG. 7, when determining, the north direction is determined by a compass, a straight line with a length of a is drawn along the north direction at one end of the fissure zone 104, a straight line with a length of b is drawn perpendicular to the north direction at the other end of the fissure zone 104, and then the trend angle δ of the fissure zone 104 is calculated according to the formula , wherein the units of a and b are meters.

[0047] As shown in FIG. 8, when determining the tendency and inclination of the fissure zone 104, the tendency is preliminarily determined by excavating the shallow part of the fissure zone 104, a profile line is drawn perpendicular to the trend of the fissure zone 104, three drill holes m1, m2, and m3 are arranged on the profile line according to intervals a1, a2, the horizontal angles of the upper boundary line of the fissure zone are respectively α1 and α2, the horizontal angles of the lower boundary line of the fissure zone are respectively β1 and β2, the distance between the drill hole m1 and the drill hole m2 on the upper boundary line of the fissure zone is t1, the distance between the drill hole m2 and the drill hole m3 on the upper boundary line of the fissure zone is t2, the distance between the drill hole m1 and the drill hole m2 on the lower boundary line of the fissure zone is t3, and the distance between the drill hole m2 and the drill hole m3 on the lower boundary line of the fissure zone is t4, and then α1, α2, β1, and β2 are sequentially obtained according to the formula , and the average of α1 and α2 is taken as the inclination of the upper boundary line of the fissure zone, and the average of β1 and β2 is taken as the inclination of the lower boundary line of the fissure zone, wherein the units of a1, a2, t1, t2, t3, and t4 are meters.

[0048] S2, a water collecting cover 2 is installed in the foundation pit, so that the water collecting cover 2 covers the area of the fissure zone 104, and the dispersed gushing points 105 in the area of the fissure zone 104 are concentrated in the water collecting cover 2, and at the same time, a steel drainage pipe 3 is welded on the top of the water collecting cover 2, and the steel drainage pipe 3 is used to discharge the gushing water at the designed water level into the foundation pit.

[0049] Specifically, as shown in FIG. 4 and FIG. 5, when installing the water collecting cover 2, an anchor steel plate 201 is processed by welding at the bottom periphery of the water collecting cover 2, a rubber strip 202 is placed at the contact surface between the bottom edge of the water collecting cover 2 and the rock, and then the anchor steel plate 201 is fixed on the rock through expansion bolts 203, so that the anchor steel plate 201 presses the rubber strip 202, thereby preventing seepage between the bottom edge of the water collecting cover 2 and the contact surface with the rock. The diameter and number of the steel drain pipes 3 are determined according to the water inflow size, and the height of the steel drain pipes 3 is 1m-2m.

[0050] S3, determining the arrangement range and arrangement mode of the grouting drill hole 5 according to the occurrence of the fracture zone 104.

[0051] Specifically, as shown in FIG. 2, the grouting drill hole 5 is arranged in parallel to the strike of the fracture zone 104 with the water inflow point 105 as the center, one row of grouting drill holes 5 is arranged on each side of the fracture zone 104, the hole spacing of each row of grouting drill holes 5 is 0.5m-2m, the drilling direction of the grouting drill hole 5 drilled to the fracture zone 104 is the dip direction of the fracture zone 104, and then not less than three rows of grouting drill holes 5 are arranged in a plum blossom shape from outside to inside along the dip direction of the fracture zone 104.

[0052] S4, piling up the counter-pressure earth platform 401 around the water collecting cover 2, so that the top surface of the counter-pressure earth platform 401 covers the arrangement range of the grouting drill hole 5, and the height of the counter-pressure earth platform 401 is at least 1m higher than the designed water level in the foundation pit.

[0053] Specifically, as shown in FIG. 2 and FIG. 3, the height of the counter-pressure earth platform 401 is h3, the water level discharged into the foundation pit is designed as h2, the units of h2 and h3 are both meters, then h3-h2≥1m, so that the water level in the foundation pit does not exceed the counter-pressure earth platform 401, so as to facilitate subsequent drilling and grouting construction on the counter-pressure earth platform 401, the shape of the counter-pressure earth platform 401 is determined according to the number of the water inflow points 105, a circular conical platform is adopted for a single water inflow point, and a rectangular conical platform is adopted for multiple water inflow points, and in this embodiment, the rectangular conical platform is preferably adopted, the bottom width of which is l1, the bottom length is l3, the top width is l2, and the top length is l4, the units of l1, l2, l3 and l4 are all meters.

[0054] S5, discharging the water inflow into the foundation pit through the steel drain pipe 3, and controlling the water level difference between the inside and outside of the foundation pit to be within 3m, and the accumulated water in the foundation pit exceeding the designed water level is discharged through a water pump.

[0055] Specifically, as shown in FIG. 2, FIG. 3 and FIG. 5, the plastic drainage pipe 301 extending to the outside of the counter-pressing soil platform 401 is connected to the steel drainage pipe 3 through the joint pipe 302, so as to facilitate drainage; the overall height of the foundation pit is h, the height from the bottom of the foundation pit 103 to the excavation surface 102 is h1, and the units of h and h1 are meters, and the water level difference between the inside and outside of the foundation pit is h-h1-h2. By controlling the water level in the foundation pit and the water level difference between the inside and outside of the foundation pit, the water pressure and flow rate of the water gushing point 105 can be reduced.

[0056] S6, according to the arrangement range and arrangement mode of the grouting borehole 5, the grouting borehole 5 is constructed on the top surface of the counter-pressing soil platform 401, and the grouting borehole 5 should penetrate the fractured zone 104 and enter the complete rock for not less than 1 m.

[0057] Specifically, the drilling machine is installed on the counter-pressing soil platform 401, the grouting borehole 5 outside the fractured zone 104 is constructed first according to the arrangement range of the grouting borehole 5, and then the grouting borehole 5 close to the water gushing point 105 is constructed.

[0058] S7, the water gushing point 105 is plugged by grouting, and the grouting sequence is converging from the outside of the fractured zone to the center of the water gushing point 105.

[0059] Specifically, as shown in FIG. 4 and FIG. 6, when plugging by grouting, one grouting borehole 5 is immediately grouted by the double-pipe double-liquid grouting method, the grouting body 501 is formed after the grouting body 501 penetrates along the rock fracture 106 under the action of the grouting pump pressure after the grouting, and then the rock fracture penetration channel is closed through the grouting body 501. The flow time of the grouting body 501 from the grouting hole bottom to the initial setting in the fractured zone is not less than 30 s, and the single-hole grouting pressure is not more than 5.0 MPa.

[0060] S8, when the water gushing point 105 is completely plugged and there is no water gushing, the grouting is stopped, then the accumulated water in the bottom of the foundation pit 103 is pumped out and the counter-pressing soil platform 401 is removed, and then the normal construction operation of the foundation pit can be resumed.

[0061] Based on the above water plugging system and the corresponding water plugging method of the rock fractured zone of the foundation pit, by measuring the length, width, trend, tendency and inclination of the fractured zone 104, the arrangement range and arrangement mode of the grouting borehole 5 are determined according to the occurrence of the fractured zone 104, so as to determine the coverage range and height of the counter-pressing soil platform 401, which is beneficial to avoid the blindness of backfilling counter-pressing soil, reduce the amount of counter-pressing soil, the number of subsequent boreholes and the grouting workload, make the borehole grouting work targeted, reduce the rescue cost, control the cost, and is very effective for the water gushing plugging of the rock fractured zone of the foundation pit bottom.

[0062] While embodiments of the application have been shown and described, it is to be understood that the embodiments described are merely exemplary of the principles and application of the present application. Numerous modifications and adaptions can be effected without departing from the spirit and scope of the present application, which is not limited to the exact construction and arrangement described. It is intended, therefore, to cover all modifications and adaptions that fall within the scope of the claims and their equivalents.

Claims

1. A method for sealing a large water inflow in a rock fracture zone of a foundation pit, characterized in that, The method comprises the following steps: S1, leveling the site of the area of the water gushing point (105) of the fissure zone (104) and determining the occurrence parameters of the fissure zone (104), the occurrence parameters of the fissure zone (104) including length, width, strike, dip direction and dip angle; S2, installing a water collecting cover (2) in the foundation pit, so that the water collecting cover (2) covers the area of the fissure zone (104) and concentrates the dispersed water gushing points (105) of the fissure zone (104) in the water collecting cover (2), and welding a steel drainage pipe (3) on the top of the water collecting cover (2); S3, determining the arrangement range and arrangement mode of the grouting drill hole (5) according to the occurrence of the fissure zone (104); S4, piling up a counter-pressure earth platform (401) around the water collecting cover (2), the top surface of the counter-pressure earth platform (401) covering the arrangement range of the grouting drill hole (5), and the height of the counter-pressure earth platform (401) being at least 1m higher than the designed water level in the foundation pit; S5, discharging the gushing water into the foundation pit through the steel drainage pipe (3), and controlling the water level difference between the inside and outside of the foundation pit to be within 3m, and discharging the water accumulated in the foundation pit above the designed water level through a water pump; S6, constructing the grouting drill hole (5) on the top surface of the counter-pressure earth platform (401) according to the arrangement range and arrangement mode of the grouting drill hole (5), and the grouting drill hole (5) should penetrate the fissure zone (104) and enter the intact rock by not less than 1m; S7, grouting and plugging the water gushing point (105), and the grouting sequence being converging from the periphery of the fissure zone (104) to the center of the water gushing point (105); S8, when the water gushing point (105) is completely plugged successfully and there is no gushing water, stopping grouting, then pumping out the accumulated water in the bottom (103) of the foundation pit and removing the counter-pressure earth platform (401).

2. The method according to claim 1, wherein the method is characterized by: The strike of the fracture zone (104) is determined by a total station instrument. When determining, the north direction is determined by a compass, a straight line with a length of a is drawn along the north direction at one end of the fracture zone (104), a straight line with a length of b is drawn perpendicular to the north direction at the other end of the fracture zone (104), and then the strike angle δ of the fracture zone (104) is calculated according to the formula .

3. The method according to claim 1, wherein the method is characterized by: When determining the tendency and dip angle of the fracture zone (104), the tendency is preliminarily determined by excavating the shallow part of the fracture zone (104), a profile line is made perpendicular to the strike of the fracture zone (104), three drill holes m1, m2 and m3 are arranged on the profile line according to intervals a1, a2, the horizontal angles of the upper boundary line of the fracture zone are respectively α1 and α2, the horizontal angles of the lower boundary line of the fracture zone are respectively β1 and β2, the distance between the drill hole m1 and the drill hole m2 on the upper boundary line of the fracture zone is t1, the distance between the drill hole m2 and the drill hole m3 on the upper boundary line of the fracture zone is t2, the distance between the drill hole m1 and the drill hole m2 on the lower boundary line of the fracture zone is t3, and the distance between the drill hole m2 and the drill hole m3 on the lower boundary line of the fracture zone is t4, and α1, α2, β1 and β2 are sequentially obtained according to the formula α1=arctan((t1+t2) / a1), α2=arctan((t1+t2) / a2), β1=arctan((t3+t4) / a1), β2=arctan((t3+t4) / a2), and the average of α1 and α2 is taken as the dip angle of the upper boundary line of the fracture zone, and the average of β1 and β2 is taken as the dip angle of the lower boundary line of the fracture zone.

4. The method according to claim 1, wherein the method is characterized by: The water collecting cover (2) is processed into a frustum shape by cutting and welding a steel plate, and the size of the water collecting cover (2) is determined according to the occurrence of the fissure zone (104), the area of the water gushing point (105) and the gushing water amount.

5. The method according to claim 1, wherein the method is characterized by: When the water collecting cover (2) is installed, an anchoring steel plate (201) is processed on the bottom periphery of the water collecting cover (2), a rubber strip (202) is arranged at the contact surface between the bottom edge of the water collecting cover (2) and the rock, and the anchoring steel plate (201) is fixed on the rock through an expansion bolt (203) to press the rubber strip (202).

6. The method according to claim 1, wherein the method is characterized by: The diameter and number of the steel drainage pipe (3) are determined according to the gushing water amount, the height of the steel drainage pipe (3) is 1m-2m, and a plastic drainage pipe (301) is connected to the steel drainage pipe (3) through a joint pipe (302) to extend to the outside of the counter-pressure earth platform (401).

7. The method according to claim 1, wherein the method is characterized by: When the arrangement range and arrangement mode of the grouting drill hole (5) are determined, the grouting drill hole (5) is arranged in parallel to the strike of the fissure zone (104) with the water gushing point (105) as the center, one row of grouting drill holes (5) is arranged on each side of the fissure zone (104) first, the hole spacing of each row of grouting drill holes (5) is 0.5m-2m, the drilling direction of the grouting drill hole (5) penetrating the fissure zone (104) is the dip direction of the fissure zone (104), and not less than three rows of grouting drill holes (5) are arranged in a quincunx shape on the dip direction of the fissure zone (104) from outside to inside.

8. The method according to claim 1, wherein the method is characterized by: The shape of the counter-pressure earth platform (401) is determined according to the number of water gushing points (105), and is circular conical in single water gushing point and rectangular conical in multiple water gushing points.

9. The method according to claim 1, wherein the method is characterized by: The core of the counter-pressure earth platform (401) is backfilled with cohesive soil, the periphery of the counter-pressure earth platform (401) is filled with medium-coarse sand or gravel soil, and the slope of the counter-pressure earth platform (401) is protected by stacking sand bags or block stones (402).

10. The method according to claim 1, wherein the method is characterized by: During grouting plugging, a double-pipe double-liquid grouting method is used immediately after a grouting hole (5) is drilled, the flow time of the slurry from the grouting hole (5) outflow port to the initial setting in the fracture zone (104) is not less than 30s, and the single-hole grouting pressure is not greater than 5.0MPa.

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