Abnormal deformation treatment method for upper-hard lower-soft extra-high steep transverse slope in construction period

Abstract

The invention relates to the field of slope prevention and control of water conservancy and hydropower engineering, in particular to a method for treating abnormal deformation of an upper-hard and lower-soft extra-high steep transverse slope during a construction period, which comprises the following steps of: constructing a three-dimensional geologic model based on multi-source data, and calibrating mechanical parameters of a rock mass and a structural surface in a manner of combining inversion analysis and field monitoring data; the synergistic effect of different supporting measures is quantified through numerical simulation, and a system treatment scheme is formed. Specific treatment is carried out according to the special failure mechanism of the composite structure with the hard upper portion and the soft lower portion, the progressive extrusion deformation characteristics of the lower soft rock are accurately recognized, the treatment strategy of deep anchoring, soft rock reinforcement and form regulation and control is adopted, anchor cables are adopted for deep reinforcement, consolidation grouting is applied for improving the mechanical property of the soft rock, and form control measures of slope ratio optimization are matched, so that the composite structure is obtained. And a multi-dimensional deformation suppression system is formed. The technical problems that in the existing abnormal deformation treatment process, supporting measures are not appropriate, a supporting scheme is lack of systematicness, and the treatment effect is poor can be solved.

Description

Technical Field

[0001] The present invention relates to the field of slope prevention and control in water conservancy and hydropower projects, and particularly to a method for treating abnormal deformation during the construction period of a super-high and steep transverse slope with hard upper part and soft lower part. Background Art

[0002] Due to complex topographical and geological features, super-high and steep slopes with hard upper part and soft lower part are widely distributed. Due to geological actions such as active crustal movement and deep river incision, such slopes exist in large numbers. These areas are often key areas for the construction of transportation infrastructure and the development of water conservancy and hydropower projects. For example, during the construction of a certain hydropower station, problems of excavation and treatment of super-high and steep slopes with hard upper part and soft lower part are frequently encountered.

[0003] During the excavation process of the super-high and steep transverse slope with hard upper part and soft lower part during the construction period, due to the significant difference in mechanical properties between the upper hard rock layer and the lower soft rock layer, the original mechanical balance is easily broken during excavation. As the slope is continuously excavated downward, the rock mass on the outer side of the slope is gradually removed, and the height of the artificial slope gradually increases. Especially with the excavation unloading and relaxation of the rock mass in the middle and lower parts, the supporting effect on the upper rock mass is greatly weakened, often triggering abnormal deformation of the slope body, manifested as composite failure modes such as tensile cracks at the slope top, shear slip at the slope foot, and creep of the soft interlayer, ultimately leading to geological disasters such as landslides and collapses.

[0004] At present, the following limitations exist in the technology for treating abnormal deformation during the construction period of the super-high and steep transverse slope with hard upper part and soft lower part:

[0005] 1) The support design mostly adopts the idea of "passive reinforcement", relying on measures such as anchor rods and retaining walls, and it is difficult to adapt to this special geological condition of hard upper part and soft lower part. For the upper hard rock layer, the anchoring depth of the anchor rod is insufficient, and it is difficult to effectively exert the anchoring effect; for the lower soft rock layer, the retaining wall is difficult to bear the huge lateral pressure and is prone to overturning and damage.

[0006] 2) The current support schemes often lack systematicness, do not fully consider the interaction relationship between the upper hard rock and the lower soft rock, and only deal with local problems, unable to fundamentally solve the problem of abnormal deformation of the slope during the construction period, resulting in poor treatment effects and always existing potential safety hazards in the project.

[0007] Therefore, there are problems in the process of treating abnormal deformation during the construction period of the super-high and steep transverse slope with hard upper part and soft lower part in the prior art, such as inappropriate support measures, lack of systematicness of the support scheme, and poor treatment effects. Summary of the Invention

[0008] The purpose of the present invention is to provide a method for treating abnormal deformation during the construction period of a super-high and steep transverse slope with hard upper part and soft lower part, which can solve the technical problems of inappropriate support measures, lack of systematicness of the support scheme, and poor treatment effects existing in the existing treatment of abnormal deformation.

[0009] To achieve the above object, the present invention provides the following technical solutions:

[0010] A method for controlling abnormal deformation during the construction period of a special high-steep transverse slope with hard upper and soft lower layers designed by the present invention includes the following steps:

[0011] Establish a three-dimensional model of the excavated slope according to the initial excavation support plan, topographic and geological data, and geophysical exploration and detection data of the special high-steep transverse slope with hard upper and soft lower layers;

[0012] Carry out geological parameter back-analysis according to the topographic and geological data and the deformation monitoring data during the construction period;

[0013] Perform a forward analysis with the rock mass mechanical parameters obtained from the back-analysis and the mechanical parameters determined by geology, and calculate the comparison analysis between the displacement value and the monitored value, and finally determine the calculation parameters of the rock mass and the structural plane;

[0014] Carry out slope stability calculation using the strength reduction method according to the calculation parameters of the rock mass and the structural plane, and determine the system treatment plan according to the slope stability calculation results, including whether to increase deep cable bolt support, consolidation grouting, and slow down the slope ratio of the lower excavated slope.

[0015] As a preferred solution, the establishment of the three-dimensional model of the excavated slope includes the strata and faults, and at the same time considers the rock mass excavation disturbance unloading relaxation zone, where the relaxation depth is determined by the unloading relaxation zone in the slope geophysical exploration and detection data and the topographic and geological data.

[0016] As a preferred solution, the geological parameters to be back-analyzed include the deformation modulus, friction coefficient, and cohesion of the rock mass and the structural plane; during the back-analysis, the deformation modulus and friction coefficient of the unloading and relaxation rock mass in the part with larger deformation are reduced by 50% - 60% of the non-unloading rock mass, and the cohesion is reduced by 20% - 50% of the non-unloading rock mass.

[0017] As a preferred solution, the working conditions for slope stability calculation include persistent conditions, transient conditions, and accidental conditions. The persistent condition refers to the normal operation condition, the transient conditions include rainfall, flood discharge, and fogging working conditions, and the accidental conditions include earthquake working conditions.

[0018] As a preferred solution, when determining the system treatment plan, if the safety factor of the stability calculation under the persistent condition already meets the requirements, then this plan is the final treatment plan;

[0019] If the safety factor of the stability calculation under the persistent condition does not meet the requirements, first increase the deep cable bolt support; if it still does not meet the requirements, continue to increase the consolidation grouting measures; if it still does not meet the requirements, slow down the slope ratio of the lower excavated slope, and finally form a system treatment plan of "deep anchorage + soft rock reinforcement + morphological regulation".

[0020] Furthermore, when adding deep anchor cable support, it specifically refers to adjusting the tonnage, row spacing, length, and anchorage range of the anchor cables.

[0021] Furthermore, when adding consolidated grouting measures, it specifically refers to adjusting the scope of consolidated grouting. The depth of consolidated grouting is determined according to the relaxation depth. When performing stability calculations, the mechanical parameters of the rock mass within the scope of consolidated grouting are increased by 20% - 30%.

[0022] Furthermore, when slowing down the slope ratio of the lower excavation slope, it is required that there is no impact on the type and position of the lower structure, or the impact is within an acceptable range.

[0023] Advantages of the present invention:

[0024] 1) The method system is logically rigorous and the implementation path is clear and definite: This method constructs a three-dimensional geological model based on multi-source data, accurately calibrates the mechanical parameters of the rock mass and structural planes through the combination of inverse analysis and on-site monitoring data, quantifies the synergistic effect of different support measures through numerical simulation, and finally forms a systematic treatment plan. This implementation path has a clear logical chain and is highly operable;

[0025] 2) The mechanism understanding is profound and the systematic protection concept is advanced: It breaks through the homogeneous treatment mode of traditional slope treatment, focuses on carrying out special treatment for the special failure mechanism of the "hard upper and soft lower" composite structure. By accurately identifying the progressive extrusion deformation characteristics of the lower soft rock, it innovatively adopts a composite treatment strategy of "deep anchorage + soft rock reinforcement + morphology control", including implementing deep reinforcement with anchor cables, using consolidated grouting to improve the mechanical properties of soft rock, and cooperating with the morphology control measures of slope ratio optimization to form a multi-dimensional deformation suppression system;

[0026] 3) The scheme design is scientific and reasonable, and the engineering economy is prominent: This method determines the threshold of key control indicators through the sensitivity analysis of support parameters, adopts dynamic feedback optimization technology, and combines the construction process monitoring data to check the support strength, ensuring that the treatment plan not only meets the technical requirements of "controllable deformation and overall stability", but also avoids resource waste caused by over-support.

[0027] The present invention can solve the technical problems of inappropriate support measures, lack of systematicness in the support plan, and poor treatment effect existing in the existing abnormal deformation treatment process. Brief Description of the Drawings

[0028] Figure 1 It is a flow chart of the present invention. Detailed Embodiments

[0029] To enable those skilled in the art to better understand the technical solution of the present invention, the implementation scheme of the present invention will be described below in conjunction with specific embodiments. However, it should be understood that the drawings are only for illustrative purposes and cannot be construed as a limitation to the present invention. The description of the positional relationship in the drawings is only for illustrative purposes and cannot be construed as a limitation to the present invention.

[0030] To solve the problems of inappropriate support measures, lack of systematic support schemes, and poor treatment effects during the treatment of abnormal deformations in the construction period of extremely high and steep transverse slopes with hard upper and soft lower layers, the present invention provides a method for treating abnormal deformations in the construction period of extremely high and steep transverse slopes with hard upper and soft lower layers. Its characteristics are as follows:

[0031] The main processes of this method include:

[0032] Step 1. Establish a three-dimensional model of the excavated slope according to the initial excavation support scheme, topographic and geological data, and geophysical exploration and detection data of the extremely high and steep transverse slope with hard upper and soft lower layers;

[0033] Step 2. Carry out inverse analysis of some geological parameters based on the topographic and geological data and deformation monitoring data during the construction period;

[0034] Step 3. Conduct a forward analysis with some rock mass mechanical parameters obtained from the inverse analysis and the mechanical parameters determined by geology, and calculate the comparative analysis of the displacement value and the monitored value, and finally determine the calculation parameters of the rock mass and the structural plane;

[0035] Step 4. Carry out slope stability calculation using the strength reduction method based on the calculation parameters of the rock mass and the structural plane, and determine the system treatment plan according to the slope stability calculation results, including whether to increase deep anchor cable support, consolidation grouting, and slow down the slope ratio of the lower excavated slope.

[0036] The geophysical exploration and detection data mentioned in Step 1 mainly refer to in-hole acoustic wave and borehole color TV detection.

[0037] The establishment of the three-dimensional model of the excavated slope includes the main strata and faults, and at the same time considers the rock mass excavation disturbance unloading and relaxation zone, where the relaxation depth is determined by the unloading and relaxation area in the geophysical exploration and detection data and topographic and geological data of the slope.

[0038] The deformation monitoring data during the construction period mentioned in Step 2 includes internal and external deformation monitoring data.

[0039] The geological parameters to be inverted mainly include the deformation modulus, friction coefficient, and cohesion of the rock mass and the structural plane; during the inverse analysis, the deformation modulus and friction coefficient of the unloading and relaxation rock mass in the part with larger deformation are reduced by 50% - 60% of the non-unloading rock mass, and the cohesion is reduced by 20% - 50% of the non-unloading rock mass.

[0040] The working conditions for slope stability calculation described in Step 4 include persistent conditions (normal operation conditions), transient conditions (such as rainfall, flood discharge atomization, etc.), and accidental conditions (seismic conditions). The strength reduction method is adopted for slope stability calculation.

[0041] When carrying out slope stability calculation, it is necessary to determine the safety factor of slope strength reserve under persistent conditions according to the actual excavation layers and support. After the excavation is completed.

[0042] When determining the system treatment plan, if the safety factor obtained from the stability calculation meets the requirements, then this plan is the final treatment plan; if the safety factor obtained from the stability calculation does not meet the requirements, then deep anchor cables support is added first; if it still does not meet the requirements, then the consolidated grouting measures are continued to be added; if it still does not meet the requirements, then the slope ratio of the lower excavation slope is slowed down, and finally a system treatment plan of "deep anchorage + soft rock reinforcement + morphology regulation" is formed.

[0043] When adding deep anchor cables support, adjustments can be made for the tonnage, row spacing, length, and anchorage range of the anchor cables.

[0044] When adding consolidated grouting measures, adjustments can be made for the scope of consolidated grouting, and the depth of consolidated grouting is determined according to the relaxation depth; when carrying out stability calculation, the mechanical parameters of the rock mass within the scope of consolidated grouting can be considered to be increased by 20% - 30%.

[0045] When slowing down the slope ratio of the lower excavation slope, it is necessary not to affect the type and position of the lower structure, or if there is an impact, it is within an acceptable range.

[0046] Example:

[0047] Taking the left slope of the outlet of a certain flood discharge tunnel as an example of a very high and steep transverse slope with hard upper and soft lower layers, during the excavation, due to the soft rock properties of the slope, the dense fractured rock mass of the structure, and at the same time, the excavation blasting aggravated the unloading relaxation depth and range, resulting in an abnormal increase in slope deformation. In order to determine the system treatment measures for the abnormal deformation, the following method is adopted:

[0048] Step 1) According to the initial excavation support plan, topographic and geological data, and geophysical exploration and detection data of the very high and steep transverse slope with hard upper and soft lower layers, establish a three-dimensional model of the left slope of the outlet of the flood discharge tunnel;

[0049] Step 2) According to the geological data and deformation monitoring data during the construction period, carry out the inversion analysis of some geological parameters;

[0050] Step 3) Carry out a forward analysis with some of the rock mass mechanical parameters obtained from the inversion analysis and the mechanical parameters determined by the geology together, compare and analyze the displacement values calculated therefrom with the monitored values, and finally determine the calculation parameters of the rock mass and the structural plane;

[0051] Step 4) Carry out slope stability calculation using the strength reduction method based on the calculated parameters of the rock mass and structural plane, and determine the systematic treatment plan according to the slope stability calculation results, including adding deep anchor cable support, consolidation grouting, and slowing down the excavation slope ratio at the lower part.

[0052] The geophysical exploration detection mentioned in Step 1) mainly refers to in-hole acoustic wave and borehole color TV detection; the 3D model of the left slope at the outlet of the flood discharge tunnel includes the main strata and faults, and at the same time, the rock mass excavation disturbance unloading relaxation zone is considered, where the relaxation depth is determined by the unloading relaxation zone in the geophysical exploration detection data and geological data of the slope.

[0053] The construction period deformation monitoring data mentioned in Step 2) includes internal and external deformation monitoring data; the geological parameters to be back-analyzed mainly include the deformation modulus, friction coefficient, and cohesion of the rock mass and structural plane; during the back-analysis, the cohesion of the unloading and relaxed rock mass at the part with larger deformation is reduced by 20% - 50% of the non-unloading rock mass, and the deformation modulus and friction coefficient are reduced by 50% - 60% of the non-unloading rock mass.

[0054] The slope stability calculation conditions mentioned in Step 4) include the persistent condition (normal operation condition), the transient condition (conditions such as rainfall and flood discharge atomization), and the accidental condition (earthquake condition), and the strength reduction method is adopted for the stability calculation method.

[0055] When carrying out slope stability calculation, according to the actual excavation stratification and support situation, when determining the systematic treatment plan, if the safety factor of the stability calculation under the persistent condition does not meet the requirements, first add deep anchor cable support. If the safety factor of the stability calculation still does not meet the requirements, then add consolidation grouting measures. If it still does not meet the requirements, finally slow down the excavation slope ratio at the lower part, and finally form a systematic treatment plan of "deep anchorage + soft rock reinforcement + morphological regulation".

[0056] After the excavation is completed, the safety factor of the slope strength reserve under the persistent condition is calculated to be 1.22, which does not meet the specification requirements;

[0057] When adding deep anchor cable support, the tonnage, row and column spacing, length, and anchorage range of the anchor cable are adjusted, and it still does not meet the specification requirements;

[0058] When adding consolidation grouting measures, the consolidation grouting range is adjusted, and the consolidation grouting depth is determined according to the relaxation depth; during the stability calculation, the mechanical parameters of the rock mass within the consolidation grouting range are increased by 20% - 30%, and the safety factor of the slope strength reserve under the normal condition is calculated to be 1.27, which still does not meet the specification requirements;

[0059] When the slope ratio of the lower excavation slope is slowed down, the slope ratio of the last stage of the slope is adjusted from 1:0.3 to 1:0.6. After the adjustment, it has an impact on the side wall structure type of the water cushion pond at the bottom of the slope, the plane position of the foundation gallery, the position of the structural joint along the flow direction, etc., but within an acceptable range. The safety factor of the slope strength reserve under the persistent condition is calculated to be 1.38, meeting the design requirements.

[0060] It should be understood that the specific order or hierarchy of steps in the disclosed process of the present invention is an example of an exemplary method. Based on design preferences, it should be understood that the specific order or hierarchy of steps in the process can be rearranged without departing from the scope of the present disclosure. The appended method claims present the elements of the various steps in an exemplary order and are not intended to be limited to the specific order or hierarchy described.

[0061] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for treating abnormal deformation of a particularly high and steep transverse slope during construction, characterized in that: The following steps are included: According to the initial excavation and support plan of the extremely high and steep transverse slope with hard upper part and soft lower part, topographic and geological data, and geophysical detection data, a three-dimensional model of the excavated slope is established; Carry out inversion analysis of geological parameters based on topographic geological data and deformation monitoring data during construction; The rock mass mechanical parameters obtained by inversion analysis and the mechanical parameters determined by geology are used for forward analysis, and the displacement values ​​are compared with the monitoring values ​​to finally determine the calculation parameters of the rock mass and structural surface. The slope stability calculation is carried out using the strength reduction method according to the calculation parameters of the rock mass and structural surface, and the system management plan is determined based on the slope stability calculation results, including whether to increase deep anchor support, consolidation grouting, and slow down the slope ratio of the lower excavation slope.

2. The method for treating abnormal deformation of a particularly high and steep transverse slope during construction with a hard upper part and a soft lower part according to claim 1, characterized in that: The establishment of the three-dimensional model of the excavated slope includes strata and faults, and takes into account the unloading relaxation zone of the rock mass excavation disturbance, wherein the relaxation depth is determined by the unloading relaxation zone in the slope geophysical detection data and the topographic and geological data.

3. The method for treating abnormal deformation of a super-high and steep transverse slope with a hard upper part and a soft lower part during construction according to claim 1, characterized in that: The geological parameters to be inverted include deformation modulus, friction coefficient and cohesion of rock mass and structural surface; during inversion analysis, the deformation modulus and friction coefficient of unloaded relaxed rock mass in the larger deformed part are reduced by 50% to 60% of that of non-unloaded rock mass, and the cohesion is reduced by 20% to 50% of that of non-unloaded rock mass.

4. The method for treating abnormal deformation of a super-high and steep transverse slope with a hard upper part and a soft lower part during construction according to claim 1, characterized in that: The operating conditions for slope stability calculation include permanent conditions, short-term conditions and accidental conditions. The permanent conditions refer to normal operating conditions, the short-term conditions include rainfall, flood discharge and fogging conditions, and the accidental conditions include earthquake conditions.

5. The method for treating abnormal deformation of a particularly high and steep transverse slope with a hard upper part and a soft lower part during construction according to claim 4, characterized in that: When determining the system governance plan, if the stability calculation safety factor under the persistent condition has met the requirements, then this plan is the final governance plan; If the safety factor of stability calculation under persistent working conditions does not meet the requirements, deep anchor support will be added first; if it still does not meet the requirements, consolidation grouting measures will continue to be added; if it still does not meet the requirements, the slope ratio of the lower excavation slope will be slowed down, and finally a systematic management plan of "deep anchoring + soft rock reinforcement + morphology control" will be formed.

6. The method for treating abnormal deformation of a particularly high and steep transverse slope during construction with a hard upper part and a soft lower part according to claim 5, characterized in that: When adding deep anchor support, specific pointers are used to adjust the anchor tonnage, spacing, length and anchoring range.

7. The method for treating abnormal deformation of a particularly high and steep transverse slope during construction according to claim 6, characterized in that: When adding consolidation grouting measures, the specific indicators are adjusted for the consolidation grouting range. The consolidation grouting depth is determined according to the relaxation depth. When performing stability calculations, the rock mechanical parameters within the consolidation grouting range are increased by 20% to 30%.

8. The method for treating abnormal deformation of a particularly high and steep transverse slope during construction with a hard upper part and a soft lower part according to claim 7, characterized in that: When slowing down the slope ratio of the lower excavation slope, it is required that there is no impact on the type and position of the lower structure, or the impact is within an acceptable range.

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