Method for rapidly evaluating rock weathering degree on high and steep slope site

Abstract

The invention relates to a method for quickly evaluating the weathering degree of rocks on a high and steep slope site, which is characterized in that the deterioration data of the rock surface hardness, the surface water absorption rate and the rock wave velocity along with the dry-wet cycle process of the rocks are obtained based on a dry-wet cycle simulation deterioration test. The invention provides a brand new rapid quantitative evaluation means for the rock weathering degree, real and reliable data support is provided for the engineering construction process, and the potential instability risk caused by the unknown rock weathering degree is avoided.

Description

Technical Field

[0001] The invention relates to the technical field of engineering safety, and in particular to a method for quickly evaluating the degree of rock weathering on-site on steep slopes. Background Art

[0002] During the monitoring process of high and steep slope projects, the degree of weathering and stability of the rock mass need to be accurately grasped to provide real, accurate, safe and reliable data support for the subsequent excavation and construction. At present, there are many methods for quickly evaluating the degree of weathering of rock masses at home and abroad, but most of these methods lack quantitative evaluation means. The surface hardness of the rock represents the degree of deterioration of the outermost exposed surface of the rock; the rock's own water absorption rate represents the degree of development of microcracks and micropores on the surface and shallow layers of the rock, and the rock wave velocity reflects the density of the rock interior. Through three evaluation methods from the outside to the inside, the weathering degree of the high and steep slope rock mass is quantitatively characterized in an all-round and multi-level manner, which is more convenient to provide a theoretical basis for engineering forecasting and excavation construction. Based on this, the present invention proposes a method for quickly and quantitatively evaluating the degree of deterioration and damage of the rock mass by coupling rock surface hardness, surface water absorption and rock wave velocity analysis. Summary of the Invention

[0003] In order to solve the problem of evaluating the degree of rock weathering for the stability of high and steep slopes and to make a rapid and accurate quantitative evaluation thereof, the present invention provides a method for on-site rapid evaluation of the degree of rock weathering on high and steep slopes.

[0004] A method for rapidly evaluating the degree of rock weathering on steep slopes, wherein: based on a dry-wet cycle simulation degradation test, data on the degradation of rock surface hardness, surface water absorption rate, and rock wave velocity during the dry-wet cycle of the rock are obtained.

[0005] Furthermore, the degradation damage index of the rock sample is defined as: K= S R + H R + W R， Where: S R is the ratio of the wave velocity of fresh rock to the wave velocity of exposed rock, H R is the ratio of the surface hardness of fresh rock to the surface hardness of exposed rock, W R is the ratio of the free water absorption rate of exposed rock to the free water absorption rate of fresh rock, The free water absorption rate is W= , where Ms is the mass of the test piece after being soaked in a water tank for 12 h, taken out, and quickly dried with a wet towel, and Md is the mass of the solid after drying to constant weight.

[0006] Furthermore, the above method was applied to the assessment of tunnel granite deterioration. Level I is K < 1.2, and the degree of deterioration damage is slightly weathered; Level II is 1.3 ≤ K < 1.5, and the degree of weathering damage is moderate; Level III is K ≥ 1.5, and the degree of deterioration damage is severe.

[0007] The present invention provides a new method for rapid quantitative evaluation of rock weathering degree, which provides real and reliable data support for the engineering construction process and avoids potential instability risks caused by unknown rock weathering degree. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 It is a schematic flow chart of a method for rapid on-site assessment of rock weathering degree on high and steep slopes. DETAILED DESCRIPTION

[0009] The method for quickly evaluating the degree of rock weathering on a steep slope provided by the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments: Example

[0010] Taking the rock samples of the steep slope at the entrance of Tianshan Shengli Tunnel as an example, based on the dry-wet cycle simulation degradation test, the degradation data of the rock surface hardness, surface water absorption rate and rock wave velocity during the dry-wet cycle process were obtained.

[0011]

[0012] According to the different degrees of impact, the degradation damage index of the rock sample is first defined K= S R + H R + W R， Among them S R is the ratio of the wave velocity of fresh rock to the wave velocity of exposed rock, H R is the ratio of the surface hardness of fresh rock to the surface hardness of exposed rock, W R It is the ratio of the free water absorption rate of exposed rock to the free water absorption rate of fresh rock. The free water absorption rate W= , where Ms is the mass of the specimen after immersion in a water tank for 12 hours, removal, and rapid drying with a wet towel. Md is the mass of the solid mass after drying to constant weight. The deterioration index is used to quickly and quantitatively assess the degree of weathering of a rock sample.

[0013] The Tianshan Victory Tunnel is an ultra-long highway tunnel. The tunnel is 22,105 meters long and has a maximum buried depth of approximately 1,150 meters. The entrance elevation is approximately 2,767 meters, and the exit elevation is approximately 2,900 meters. It starts on the west side of the G30 Cangfanggou Interchange in Urumqi City, connecting to the Xishan South Interchange of the planned West Ring Expressway (the Xishan South Interchange is included in the implementation of the West Ring Expressway), crossing the Tianshan area and ending in Qiongkule Village on the east side of Yuli County. The total length of the route is 318.511 kilometers. This tunnel is designed using a three-tunnel scheme with a service tunnel set between two main tunnels. The main tunnel is constructed using a highly mechanized drilling and blasting method, while the service tunnel is constructed using the TBM method.

[0014] Under current construction conditions, the varying degrees of weathering on the steep slopes at tunnel entrances have become a significant threat to tunnel construction safety. Furthermore, the combined effects of seepage, condensation, capillary water, and air pollutants on these steep slopes pose a serious threat to tunnel construction safety.

[0015] Surface hardness, free water absorption, and wave velocity tests were conducted on rock samples from the steep ramp at the tunnel entrance. A total of 12 weathered and exfoliated rock samples, numbered TS-1 through TS-12, were tested. Fresh rock samples were taken from fresh cores at the same level.

[0016]

[0017] The granite deterioration index for the Tianshan Shengli Tunnel ranges from 1.03 to 1.71. Based on this range, the granite weathering degree is classified as Grade I, Grade II, and Grade III. Grade I, with K < 1.2, indicates slightly deteriorated damage; Grade II, with K 1.3 ≤ K < 1.5, indicates moderate weathering damage; and Grade III, with K ≥ 1.5, indicates severe deterioration damage. The service tunnel of the Tianshan Shengli Tunnel is slightly weathered, the main tunnel (faces 3 and 5) of the Tianshan Shengli Tunnel exhibits moderate weathering damage, and the main tunnel (face 4) of the Tianshan Shengli Tunnel exhibits severe weathering damage.

[0018] The examples of the present invention are described in detail above in conjunction with the embodiments, but the present invention is not limited to the above examples. Various changes can be made within the knowledge of ordinary technicians in this field without departing from the purpose of the present invention, and should also be regarded as the scope of protection of the present invention.

Claims

1. A method for rapidly evaluating the degree of rock weathering on steep slopes, characterized in that: Based on the dry-wet cycle simulation degradation test, the degradation data of rock surface hardness, surface water absorption rate and rock wave velocity during the dry-wet cycle of rock were obtained.

2. The method for rapid on-site evaluation of rock weathering degree on steep slopes according to claim 1 is characterized in that: Define the deterioration damage index of the rock sample: K= S R + H R + W R Where: S R is the ratio of the wave velocity of fresh rock to the wave velocity of exposed rock, H R is the ratio of the surface hardness of fresh rock to the surface hardness of exposed rock, W R is the ratio of the free water absorption rate of exposed rock to the free water absorption rate of fresh rock, The free water absorption rate is W= , where Ms is the mass of the test piece after being soaked in a water tank for 12 h, taken out, and quickly dried with a wet towel, and Md is the mass of the solid after drying to constant weight.

3. The method for rapid on-site evaluation of rock weathering degree on steep slopes according to claim 2, characterized in that: Applied to tunnel granite deterioration assessment, Level I is K<1.2, and the degree of deterioration damage is slightly weathered; Level II is 1.3≤K<1.5, and the degree of weathering damage is moderate; Level III is K≥1.5, and the degree of deterioration damage is severe.

Images