Construction method for dense crossing of long and large tunnel through fault fracture zone

Abstract

The invention relates to the technical field of tunnel construction, in particular to a construction method for a long and large tunnel to densely penetrate through a fault fracture zone, which comprises the following steps of: S1, marking advanced geological exploration hole sites on a tunnel face by using red paint, dragging a down-the-hole drill to a working position after the hole sites are arranged, aligning the hole sites and fixing the drill, aligning the front end of the drilling tool to a hole position on the tunnel face, then adjusting the direction of the drilling tool, measuring the position of the tail end of the drilling tool by using a total station, adjusting the position to a designed space point position, starting the down-the-hole drilling tool, and carrying out horizontal geological drilling on the tunnel face by the down-the-hole drilling tool to obtain geological information; processing according to the acquired geological information and the stratum, lithology and joint fissure characteristic information to obtain surrounding rock integrity evaluation, and generating a geological cloud map by utilizing the surrounding rock integrity evaluation; the problems that an existing fault fracture zone construction method is complex in construction process, the danger degree in the construction process cannot be reduced, and construction safety is affected can be effectively solved.

Description

Technical Field

[0001] The invention relates to the technical field of tunnel construction, and in particular to a construction method for a long tunnel densely crossing a fault fracture zone. Background Art

[0002] Fault crushing zone refers to the relative movement of the two plates of the fault, which squeeze each other and crush the nearby rocks to form a crushing zone roughly parallel to the fault plane, referred to as the fault zone. It is the main factor affecting construction safety and efficiency in tunnel construction. However, the existing fault crushing zone construction method still has shortcomings. Specifically, the existing fault crushing zone construction method has a complicated construction process and cannot reduce the degree of danger during the construction process, affecting construction safety.

[0003] Therefore, a construction method for long and large tunnels densely crossing fault fracture zones is needed to solve the problems raised in the above background technology. Summary of the invention

[0004] The purpose of the present invention is to provide a construction method for a long tunnel densely crossing a fault fracture zone to solve the problems raised in the above-mentioned background technology.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] A construction method for a long tunnel densely crossing a fault fracture zone comprises the following steps:

[0007] S1, mark the advanced geological exploration hole positions on the tunnel face with red paint. After the hole positions are arranged, drag the down-the-hole drill to the working position, align the hole positions and fix the drill, align the front end of the drill with the hole positions on the tunnel face, and then adjust the drill position. Use the total station to measure the position of the drill tail end and adjust it to the designed spatial point position. Start the down-the-hole drill. The down-the-hole drill performs horizontal geological drilling on the tunnel face to obtain geological information. The surrounding rock integrity evaluation is obtained based on the acquired geological information and the formation, lithology and joint fissure characteristics information. The surrounding rock integrity evaluation is used to generate a geological cloud map;

[0008] S2, according to the geological cloud map, an advance pipe shed is set at the fault fracture zone, the first grouting hole is drilled on the upper advance pipe shed, and then a glass fiber anchor is set on the heading face, and the second grouting hole is started on the glass fiber anchor, and grouting is injected into the first grouting hole and the second grouting hole. The maximum pressure of the grouting port is strictly controlled within 0.5Mpa to prevent fracturing of the working face, and the grouting speed is controlled. The grouting amount in each conduit is determined by calculation. If the pressure rises and the flow rate decreases, although the grouting amount does not reach the calculated value, the orifice pressure has reached 0.5Mpa, and the grouting is terminated. A hanging net is installed on the advance pipe shed, and a dense steel arch frame is used for support. The spacing between adjacent dense steel arch frames is less than 90 cm. Concrete or fiber concrete is sprayed on the dense steel arch frame and the hanging net and wait for solidification;

[0009] S3, identify the internal structure of the fault fracture zone according to the geological cloud map, obtain the fault fracture zone entity model after gridding the fault fracture zone, construct the conductivity and plugging model of the fault fracture zone in the fault fracture zone entity model, and divide the tunnel face into weak water zone, basic zone and strong water zone according to the conductivity and plugging model of the fault fracture zone. Then, determine the grouting holes and drainage holes according to the water inflow of the zones and the geological conditions, drill drainage holes and grouting holes on the tunnel face to form drainage hole layers and grouting hole layers, and construct a grouting stop wall to implement grouting on the tunnel face. During grouting, adopt the grouting local division and diagonal drainage guiding grouting method to increase the spatial distance between grouting and drainage holes. After the grouting is completed, open the drainage hole immediately. If the drainage hole is blocked by grouting, re-drill the drainage hole immediately and start using pumping for active drainage;

[0010] S4. After the drainage is completed, combined with the actual geological conditions in the tunnel, weak blasting excavation is adopted, and the excavation cycle advance is strictly controlled, with each cycle controlled at 0.4m-0.8m. The excavation method adopts the three-step temporary inverted arch method to avoid the danger of causing a suspended arch when the lower half of the section is excavated. The maximum excavation length of each step shall not exceed 2m-15m. When large-scale water seepage occurs on the excavation face or cracks are found on the excavation face, secondary grouting holes are drilled on the rock mass to be excavated, a grouting stop wall is constructed, and secondary grouting reinforcement is carried out. After the excavation is completed, the excavated tunnel is supported.

[0011] As a preferred solution of the present invention, when drilling in S1, a group of advanced geological detection holes are opened on the upper step arch, the left and right sides of the middle step, and the left and right sides of the lower step of each cross-section. The length of a single detection hole is 20m-40m, and the overlap distance between adjacent detection holes is 3m-7m.

[0012] As a preferred solution of the present invention, the method for obtaining the surrounding rock integrity evaluation in S1 is: obtaining geological information data such as rock type, rock joints and rock distribution according to the core in the borehole, determining the rock structural surface according to the rock distribution, extracting rock direction, density, morphology and roughness characteristics based on the rock feature extraction template and relying on rock joints and rock structural surfaces, determining the stability value corresponding to the rock feature according to the corresponding preset stability evaluation library, summing the stability values ​​to obtain the first stability, inputting the rock feature into the rock fault activity model to obtain the degree of rock fault activity and determine the fault displacement rate, fault length and extension direction, using the fault displacement rate, fault length and extension direction to determine the correction weight, using the correction weight to correct the first stability to determine the second stability, bringing the second stability and the formation, lithology and joint fissure feature information into the rock evaluation model to obtain the surrounding rock integrity evaluation.

[0013] As a preferred solution of the present invention, the method for determining the correction weight is as follows: input the fault displacement rate, fault length, and extension direction into the preview model, obtain the preview result output by the preview model, compare the preview result with the current activity level, determine the comparison difference item between the preview result and the current result, determine the correction direction and correction value according to the comparison difference item, and determine the correction coefficient. Accumulate the correction coefficients corresponding to all comparison difference items to obtain the correction weight.

[0014] As a preferred solution of the present invention, the method for determining the grouting volume in S2 is as follows: during grouting, calculate the permeability coefficient after grouting every 30S according to the seepage formula. When the calculated permeability coefficient continues to increase, continue grouting until the calculated permeability coefficient begins to continuously decrease and is maintained for 1 - 2 minutes. At this time, stop grouting and reinforcement.

[0015] As a preferred solution of the present invention, the seepage formula is where L represents the length of the grouting section, represents the grouting pressure, represents the stable flow rate during grouting, K represents the permeability coefficient after grouting, γ represents the radius of the grouting hole, and lg represents the logarithm with base 10.

[0016] As a preferred solution of the present invention, the division standard for the weak water area in S3 is that the water volume Q ≤ 10 m / h, the division standard for the basic area is that the water volume 10 < Q ≤ 30 m / h, and the division standard for the strong water area is that the water volume Q > 30 m / h. The grout stop wall is divided into 5 grades. The thickness of the grout stop wall for I - II grade surrounding rock is 2 m, the thickness of the grout stop wall for II - III grade surrounding rock is 3 m, and the thickness of the grout stop wall for IV - V grade surrounding rock is 4 m. The grout stop wall is made by pouring with high - performance concrete materials. The average maximum slurry absorption volume per single drain hole is 20 m 3 , and one drain hole is provided at each of the four corners of the heading face. A drain pipe is provided in the drain hole, and a valve is provided on the drain pipe.

[0017] As a preferred solution of the present invention, the specific method for tunnel support in S4 is as follows: after excavation, initially spray concrete. Before spraying, deal with dangerous rocks, check the clearance size of the excavation section, wash the sprayed surface with high - pressure air and water, set marks for controlling the thickness of the sprayed concrete, position the shotcrete robot, adjust the nozzle position to make it perpendicular to the rock face. The nozzle is perpendicular to the rock face, 0.8 m - 1.2 m away from the sprayed surface, and moves in a spiral shape. The air pressure is 0.5 MPa - 0.7 MPa. The liquid accelerator is automatically metered and added at the nozzle. When spraying concrete, it is carried out in sequence by construction process section and piece, from bottom to top. The maximum thickness of a single shotcrete is not more than 10 cm for the arch part and not more than 15 cm for the side wall. The next layer of spraying should be carried out after the previous layer of concrete has set.

[0018] Compared with the prior art, the beneficial effects of the present invention are:

[0019] 1. In the present invention, horizontal geological drilling is carried out on the tunnel face by a down-the-hole drill to obtain geological information, and the surrounding rock integrity evaluation is obtained based on the acquired geological information and the information of the formation, lithology and joint fissure characteristics. The surrounding rock integrity evaluation is used to generate a geological cloud map, and an advance pipe shed is set at the fault fracture zone according to the geological cloud map, and a first grouting hole is drilled on the upper advance pipe shed, and then a fiberglass anchor is set on the face, and a second grouting hole is started on the fiberglass anchor, and grouting is injected into the first grouting hole and the second grouting hole, and the grouting is terminated. A hanging net is installed on the advance pipe shed, and a dense steel arch frame is used for support, and the spacing between adjacent dense steel arch frames is less than 90 cm. Concrete or fiber concrete is sprayed on the dense steel arch frame and the hanging net and waits for solidification, and the fault fracture zone position in the tunnel is reinforced before the construction starts, thereby reducing the probability of danger during construction. At the same time, according to the geological cloud map recognition and processing, after A fault fracture zone entity model is obtained, and a conductivity and sealing model of the fault fracture zone is constructed in the fault fracture zone entity model. The tunnel face is zoned and located according to the conductivity and sealing model of the fault fracture zone, and the tunnel face hole distribution range is divided into weak water zone, basic zone and strong water zone. Drainage holes and grouting holes are drilled on the tunnel face to form a drainage hole layer and a grouting hole layer, and a grouting stop wall is constructed, which can greatly reduce the probability of water seepage during construction of the fault fracture zone and further improve the construction safety. After drainage is completed, combined with the actual geological conditions in the tunnel, weak blasting excavation is adopted, and the excavation cycle advance is strictly controlled. After excavation is completed, the excavated tunnel is supported. A complete tunnel detection is carried out before construction. According to the detection results, the fault fracture zone in the tunnel is supported and drained, which reduces the degree of danger in the construction of the fault fracture zone. After excavation is completed, the tunnel is further supported to improve the safety of the tunnel. DETAILED DESCRIPTION

[0020] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0021] Several embodiments of the present invention are given below; however, the present invention may be implemented in many different forms and is not limited to the embodiments described herein; on the contrary, these embodiments are provided to make the disclosure of the present invention more thorough and comprehensive.

[0022] It should be noted that when an element is referred to as being "fixed on" another element, it may be directly on the other element or there may also be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may also be a central element. The terms "vertical", "horizontal", "left", "right" and similar expressions used in this article are for illustrative purposes only.

[0023] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by technicians in the technical field to which the present invention belongs. The terms used in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0024] Embodiment, the present invention provides a technical solution:

[0025] A construction method for a long tunnel densely crossing a fault fracture zone comprises the following steps:

[0026] S1, mark the advanced geological exploration hole positions on the tunnel face with red paint. After the hole positions are arranged, drag the down-the-hole drill to the working position, align the hole positions and fix the drill, align the front end of the drill with the hole positions on the tunnel face, and then adjust the drill position. Use the total station to measure the position of the drill tail end and adjust it to the designed spatial point position. Start the down-the-hole drill. The down-the-hole drill performs horizontal geological drilling on the tunnel face to obtain geological information. The surrounding rock integrity evaluation is obtained based on the acquired geological information and the formation, lithology and joint fissure characteristics information. The surrounding rock integrity evaluation is used to generate a geological cloud map;

[0027] S2, according to the geological cloud map, an advance pipe shed is set at the fault fracture zone, the first grouting hole is drilled on the upper advance pipe shed, and then a glass fiber anchor is set on the heading face, and the second grouting hole is started on the glass fiber anchor, and grouting is injected into the first grouting hole and the second grouting hole. The maximum pressure of the grouting port is strictly controlled within 0.5Mpa to prevent fracturing of the working face, and the grouting speed is controlled. The grouting amount in each conduit is determined by calculation. If the pressure rises and the flow rate decreases, although the grouting amount does not reach the calculated value, the orifice pressure has reached 0.5Mpa, and the grouting is terminated. A hanging net is installed on the advance pipe shed, and a dense steel arch frame is used for support. The spacing between adjacent dense steel arch frames is less than 90 cm. Concrete or fiber concrete is sprayed on the dense steel arch frame and the hanging net and wait for solidification;

[0028] S3, identify the internal structure of the fault fracture zone according to the geological cloud map, obtain the fault fracture zone entity model after gridding the fault fracture zone, construct the conductivity and plugging model of the fault fracture zone in the fault fracture zone entity model, and divide the tunnel face into weak water zone, basic zone and strong water zone according to the conductivity and plugging model of the fault fracture zone. Then, determine the grouting holes and drainage holes according to the water inflow of the zones and the geological conditions, drill drainage holes and grouting holes on the tunnel face to form drainage hole layers and grouting hole layers, and construct a grouting stop wall to implement grouting on the tunnel face. During grouting, adopt the grouting local division and diagonal drainage guiding grouting method to increase the spatial distance between grouting and drainage holes. After the grouting is completed, open the drainage hole immediately. If the drainage hole is blocked by grouting, re-drill the drainage hole immediately and start using pumping for active drainage;

[0029] S4. After the drainage is completed, combined with the actual geological conditions in the tunnel, weak blasting excavation is adopted, and the excavation cycle advance is strictly controlled, with each cycle controlled at 0.4m-0.8m. The excavation method adopts the three-step temporary inverted arch method to avoid the danger of causing a suspended arch when the lower half of the section is excavated. The maximum excavation length of each step shall not exceed 2m-15m. When large-scale water seepage occurs on the excavation face or cracks are found on the excavation face, secondary grouting holes are drilled on the rock mass to be excavated, a grouting stop wall is constructed, and secondary grouting reinforcement is carried out. After the excavation is completed, the excavated tunnel is supported.

[0030] Furthermore, when drilling in S1, a group of advanced geological detection holes are opened on the upper step arch, the left and right sides of the middle step, and the left and right sides of the lower step of each section. The length of a single detection hole is 20m-40m, and the overlap distance between adjacent detection holes is 3m-7m.

[0031] Furthermore, the method for obtaining the surrounding rock integrity evaluation in S1 is as follows: geological information data such as rock type, rock joints and rock distribution are obtained based on the core in the borehole, rock structural planes are determined based on the rock distribution, rock characteristics such as direction, density, shape and roughness are extracted based on the rock characteristics extraction template and relying on rock joints and rock structural planes, stability values ​​corresponding to the rock characteristics are determined according to the corresponding preset stability evaluation library, the stability values ​​are summed up to obtain a first stability, the rock characteristics are input into a rock fault activity model to obtain the degree of rock fault activity and determine the fault displacement rate, fault length and extension direction, the fault displacement rate, fault length and extension direction are used to determine the correction weight, the first stability is corrected using the correction weight to determine a second stability, the second stability and the formation, lithology and joint fissure characteristic information are brought into the rock evaluation model to obtain the surrounding rock integrity evaluation.

[0032] Further, the method for determining the correction weight is as follows: input the fault displacement rate, fault length, and extension direction into the preview model, obtain the preview result output by the preview model, compare the preview result with the current activity level, determine the comparison difference item between the preview result and the current result, determine the correction direction, correction value, and correction coefficient according to the comparison difference item, accumulate the correction coefficients corresponding to all comparison difference items, and obtain the correction weight.

[0033] Further, the method for determining the grouting volume in S2 is as follows: during grouting, calculate the permeability coefficient after grouting every 30S according to the seepage formula. When the calculated permeability coefficient continues to increase, continue grouting until the calculated permeability coefficient begins to continuously decrease and remains for 1 - 2 minutes. At this time, stop grouting and reinforcement.

[0034] Further, the seepage formula is where L represents the length of the grouting section, represents the grouting pressure, represents the stable flow rate during grouting, K represents the permeability coefficient after grouting, γ represents the radius of the grouting hole, and lg represents the logarithm with base 10.

[0035] Further, the division standard for the weak water area in S3 is that the water volume Q ≤ 10 m / h, the division standard for the basic area is that the water volume 10 < Q ≤ 30 m / h, and the division standard for the strong water area is that the water volume Q > 30 m / h. The grout stop wall is divided into 5 grades. The thickness of the grout stop wall for I - II grade surrounding rock is 2 m, the thickness of the grout stop wall for II - III grade surrounding rock is 3 m, and the thickness of the grout stop wall for IV - V grade surrounding rock is 4 m. The grout stop wall is made by pouring with high - performance concrete materials. The average maximum slurry absorption volume of a single drainage hole is 20 m 3 , and one drainage hole is provided at each of the four corners of the heading face. A drain pipe is provided in the drainage hole, and a valve is provided on the drain pipe.

[0036] Further, the specific method for tunnel support in S4 is as follows: after excavation, initially spray concrete. Before spraying, handle dangerous rocks, check the net clear dimension of the excavation section, wash the sprayed surface with high - pressure wind and water, set marks for controlling the thickness of the sprayed concrete, position the shotcrete robot, adjust the nozzle position to make it perpendicular to the rock face. The nozzle is perpendicular to the rock face, 0.8 m - 1.2 m away from the sprayed surface, and moves in a spiral. The air pressure is 0.5 MPa - 0.7 MPa. The liquid accelerator is automatically metered and added at the nozzle. When spraying concrete, it is carried out in sequence by construction process section and piece, from bottom to top. The maximum thickness of a single - layer sprayed concrete, for the arch part, does not exceed 10 cm, and for the side wall, does not exceed 15 cm. The subsequent spraying should be carried out after the previous layer of concrete has set.

[0037] Specific implementation cases

[0038] The advanced geological exploration holes are marked on the tunnel face with red paint. A group of advanced geological exploration holes are opened on the upper step vault, the left and right sides of the middle step, and the left and right sides of the lower step of each cross-section layer. The length of a single exploration hole is 20m, and the overlap distance between adjacent exploration holes is 3m. After the hole positions are arranged, the down-the-hole drill is dragged to the working position, the hole positions are aligned and fixed, the front end of the drill tool is aligned with the hole position on the tunnel face, and then the azimuth of the drill is adjusted. The position of the tail end of the drill tool is measured with a total station and adjusted to the designed spatial point. The down-the-hole drill is started and the down-the-hole drill performs horizontal geological drilling on the tunnel face to obtain geological information.

[0039] Obtain geological information data such as rock type, rock joints and rock distribution according to the core in the borehole, determine the rock structure surface according to the rock distribution, extract the rock direction, density, shape and roughness characteristics based on the rock feature extraction template and rely on the rock joints and rock structure surface, determine the stability value corresponding to the rock feature according to the corresponding preset stability evaluation library, sum the stability values ​​to obtain the first stability, input the rock feature into the rock fault activity model to obtain the rock fault activity degree and determine the fault displacement rate, fault length and extension direction;

[0040] Input the displacement rate, length and extension direction of the fault into the preview model, obtain the preview results output by the preview model, compare the preview results with the current activity level, determine the comparison difference items between the preview results and the current results, determine the correction direction and correction value and the correction coefficient according to the comparison difference items, accumulate the correction coefficients corresponding to all the comparison difference items, obtain the correction weight, use the correction weight to correct the first stability, determine the second stability, bring the second stability and the formation, lithology and joint fissure characteristics information into the rock mass evaluation model, and obtain the surrounding rock integrity evaluation. Generate a geological cloud map using the surrounding rock integrity evaluation;

[0041] According to the geological cloud map, an advance pipe shed is set up at the fault fracture zone, the first grouting hole is drilled on the upper advance pipe shed, and then a fiberglass anchor is set up on the tunnel face, and the second grouting hole is started on the fiberglass anchor. Grouting is injected into the first and second grouting holes. During grouting, the grouting is performed every 30 seconds according to the Calculate the permeability coefficient after grouting, where L represents the length of the grouting section, represents the grouting pressure, Q represents the stable flow rate during grouting, K represents the permeability coefficient after grouting, γ represents the radius of the grouting hole, lg represents the logarithm with base 10. When the calculated permeability coefficient continues to increase, continue grouting until the calculated permeability coefficient starts to continuously decrease and remains stable for 2 minutes. At this time, stop grouting and reinforcement. The maximum pressure at the grouting port is strictly controlled within 0.5 Mpa to prevent fracturing the working face. Control the grouting speed. The grouting volume in each conduit is determined by calculation. If the pressure rises and the flow rate decreases, although the grouting volume has not reached the calculated value, but the orifice pressure has reached 0.5 Mpa, end the grouting;

[0042] Install wire mesh on the advanced pipe shed and use densified steel arch frames for support. The spacing between adjacent densified steel arch frames is less than 90 cm. Spray concrete or fiber concrete on the densified steel arch frames and wire mesh and wait for it to solidify;

[0043] Identify the internal structure of the fault fracture zone based on the geological cloud map. After meshing the fault fracture zone, obtain the solid model of the fault fracture zone. Construct the conductivity and plugging models of the fault fracture zone in the solid model of the fault fracture zone. Locate the face according to the conductivity and plugging models of the fault fracture zone. Divide the hole layout range of the face into a weak water area, a basic area, and a strong water area. The division standard for the weak water area is water volume Q ≤ 10 m / h, the division standard for the basic area is water volume 10 < Q ≤ 30 m / h, and the division standard for the strong water area is water volume Q > 30 m / h. Then, determine the grouting holes and drainage holes according to the sectional water inflow and geological conditions. Drill drainage holes and grouting holes on the face. The average maximum slurry absorption volume of a single drainage hole is 20 m 3 ; one drainage hole is provided at each of the four corners of the face. A drain pipe is provided in the drainage hole, and a valve is provided on the drain pipe to form a drainage hole layer and a grouting hole layer, and construct a grout stop wall. The grout stop wall is divided into 5 grades. The thickness of the grout stop wall for I-II grade surrounding rock is 2 m, the thickness of the grout stop wall for II-III grade surrounding rock is 3 m, and the thickness of the grout stop wall for IV-V grade surrounding rock is 4 m. The grout stop wall is made by pouring with high-performance concrete materials. Implement grouting on the face. During grouting, use the grouting local division and diagonal drainage guiding grouting method to increase the spatial distance between the grouting and drainage holes. After grouting is completed, immediately open the drainage holes. If the drainage holes are blocked by grouting, immediately re-drill the drainage holes and start active drainage using a pump;

[0044] After drainage is completed, in combination with the actual geological conditions in the tunnel, use weak blasting for excavation and strictly control the excavation cycle footage, with each cycle controlled at 0.4 m. The excavation method uses the three-step temporary inverted arch method to avoid the danger of the suspended arch during the excavation of the lower half section. The excavation length of each step is at most 2 m. When a large area of water seepage appears on the driving face or it is found that the driving face has developed fissures, drill secondary grouting holes on the rock mass to be excavated and construct a grout stop wall for secondary grouting and reinforcement;

[0045] After the excavation is completed, check the clearance size of the excavation section, flush the sprayed surface with high-pressure wind and water, set the mark to control the thickness of the concrete spraying, put the concrete spraying manipulator in place, adjust the nozzle position to make it perpendicular to the rock surface, the nozzle is perpendicular to the rock surface, 0.8m away from the sprayed surface, moves in a spiral, the wind pressure is 0.5MPa, and the liquid accelerator is added at the nozzle by automatic metering. When spraying concrete, follow the construction process sections and pieces, from bottom to top in sequence. The maximum thickness of the concrete sprayed at one time shall not exceed 10cm for the arch and 15cm for the side wall. The latter layer of spraying shall be carried out after the previous layer of concrete has finally set.

[0046] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A construction method for long and large tunnels densely crossing fault fracture zones, It is characterized in that The following steps are involved: S1, mark the advanced geological exploration hole positions on the tunnel face with red paint. After the hole positions are arranged, drag the down-the-hole drill to the working position, align the hole positions and fix the drill, align the front end of the drill with the hole positions on the tunnel face, and then adjust the drill position. Use the total station to measure the position of the drill tail end and adjust it to the designed spatial point position. Start the down-the-hole drill. The down-the-hole drill performs horizontal geological drilling on the tunnel face to obtain geological information. The surrounding rock integrity evaluation is obtained based on the acquired geological information and the formation, lithology and joint fissure characteristics information. The surrounding rock integrity evaluation is used to generate a geological cloud map; S2, according to the geological cloud map, an advance pipe shed is set at the fault fracture zone, the first grouting hole is drilled on the upper advance pipe shed, and then a glass fiber anchor is set on the heading face, and the second grouting hole is started on the glass fiber anchor, and grouting is injected into the first grouting hole and the second grouting hole. The maximum pressure of the grouting port is strictly controlled within 0.5Mpa to prevent fracturing of the working face, and the grouting speed is controlled. The grouting amount in each conduit is determined by calculation. If the pressure rises and the flow rate decreases, although the grouting amount does not reach the calculated value, the orifice pressure has reached 0.5Mpa, and the grouting is terminated. A hanging net is installed on the advance pipe shed, and a dense steel arch frame is used for support. The spacing between adjacent dense steel arch frames is less than 90 cm. Concrete or fiber concrete is sprayed on the dense steel arch frame and the hanging net and wait for solidification; S3, identify the internal structure of the fault fracture zone according to the geological cloud map, obtain the fault fracture zone entity model after gridding the fault fracture zone, construct the conductivity and plugging model of the fault fracture zone in the fault fracture zone entity model, and divide the tunnel face into weak water zone, basic zone and strong water zone according to the conductivity and plugging model of the fault fracture zone. Then, determine the grouting holes and drainage holes according to the water inflow of the zones and the geological conditions, drill drainage holes and grouting holes on the tunnel face to form drainage hole layers and grouting hole layers, and construct a grouting stop wall to implement grouting on the tunnel face. During grouting, adopt the grouting local division and diagonal drainage guiding grouting method to increase the spatial distance between grouting and drainage holes. After the grouting is completed, open the drainage hole immediately. If the drainage hole is blocked by grouting, re-drill the drainage hole immediately and start using pumping for active drainage; S4. After the drainage is completed, combined with the actual geological conditions in the tunnel, weak blasting excavation is adopted, and the excavation cycle advance is strictly controlled, with each cycle controlled at 0.4m-0.8m. The excavation method adopts the three-step temporary inverted arch method to avoid the danger of causing a suspended arch when the lower half of the section is excavated. The maximum excavation length of each step shall not exceed 2m-15m. When large-scale water seepage occurs on the excavation face or cracks are found on the excavation face, secondary grouting holes are drilled on the rock mass to be excavated, a grouting stop wall is constructed, and secondary grouting reinforcement is carried out. After the excavation is completed, the excavated tunnel is supported.

2. A method for constructing a long tunnel that densely crosses a fault fracture zone according to claim 1, Features: When drilling in S1, a group of advanced geological detection holes are opened on the upper step arch, the left and right sides of the middle step, and the left and right sides of the lower step of each section layer. The length of a single detection hole is 20m-40m, and the overlap distance between adjacent detection holes is 3m-7m.

3. The method for constructing a long tunnel densely crossing a fault fracture zone according to claim 1, Features: The method for obtaining the surrounding rock integrity evaluation in S1 is as follows: obtaining geological information data such as rock type, rock joints and rock distribution according to the core in the borehole, determining the rock structural surface according to the rock distribution, extracting the rock direction, density, shape and roughness characteristics based on the rock feature extraction template and relying on the rock joints and rock structural surface, determining the stability value corresponding to the rock feature according to the corresponding preset stability evaluation library, summing up the stability values ​​to obtain the first stability, inputting the rock feature into the rock fault activity model to obtain the degree of rock fault activity and determine the fault displacement rate, fault length and extension direction, using the fault displacement rate, fault length and extension direction to determine the correction weight, using the correction weight to correct the first stability to determine the second stability, bringing the second stability and the formation, lithology and joint fissure feature information into the rock evaluation model to obtain the surrounding rock integrity evaluation.

4. A method for constructing a long tunnel densely crossing a fault fracture zone according to claim 3, Features: The method for determining the correction weight is as follows: inputting the fault displacement rate, fault length and extension direction into the preview model, obtaining the preview results output by the preview model, comparing the preview results with the current activity level, determining the comparison difference items between the preview results and the current results, determining the correction direction and correction value and the correction coefficient based on the comparison difference items, accumulating the correction coefficients corresponding to all the comparison difference items, and obtaining the correction weight.

5. The method for constructing a long tunnel densely crossing a fault fracture zone according to claim 1, Features: The method for determining the grouting amount in S2 is: during grouting, the permeability coefficient after grouting is calculated according to the permeability formula every 30 seconds. When the calculated permeability coefficient continues to increase, grouting is continued until the calculated permeability coefficient begins to decrease continuously and is maintained for 1-2 minutes, at which time grouting reinforcement is stopped.

6. A method for constructing a long tunnel that densely crosses a fault fracture zone according to claim 5, Features: The penetration formula is Where L represents the length of the grouting section, represents the grouting pressure, represents the stable flow rate during grouting, K represents the permeability coefficient after grouting, γ represents the radius of the grouting hole, and lg represents the logarithm with base 10.

7. The method for constructing a long tunnel densely crossing a fault fracture zone according to claim 1, Features: The division criteria for the weak water area in S3 are water volume Q ≤ 10 m / h, the division criteria for the basic area are water volume 10 < Q ≤ 30 m / h, and the division criteria for the strong water area are water volume Q > 30 m / h. The grout stop wall is divided into 5 grades. The thickness of the grout stop wall for surrounding rock of grade I-II is 2 m, the thickness of the grout stop wall for surrounding rock of grade II-III is 3 m, and the thickness of the grout stop wall for surrounding rock of grade IV-V is 4 m. The grout stop wall is made by pouring with high-performance concrete materials. The average maximum slurry absorption volume of a single drainage hole is 20 m 3 , and one drainage hole is provided at each of the four corners of the heading face. A drain pipe is provided in the drainage hole, and a valve is provided on the drain pipe.

8. The method for constructing a long tunnel that densely crosses a fault fracture zone according to claim 1, Features: The specific method of S4 tunnel support is as follows: initial concrete spraying after excavation, dangerous rocks treatment before spraying, checking the clearance size of the excavation section, flushing the sprayed surface with high-pressure wind and water, setting a mark to control the thickness of the sprayed concrete, putting the sprayed concrete manipulator in place, adjusting the nozzle position to make it perpendicular to the rock surface, the nozzle is perpendicular to the rock surface, 0.8m-1.2m away from the sprayed surface, moving in a spiral, wind pressure 0.5MPa-0.7MPa, liquid quick-setting agent is added at the nozzle by automatic metering, and concrete is sprayed in accordance with the construction process section and segmentation, from bottom to top in sequence. The maximum thickness of the sprayed concrete at one time shall not exceed 10cm for the arch and 15cm for the side wall. The latter layer of spraying shall be carried out after the previous layer of concrete has finally set.

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