Method for detecting shield channel influence area karst under building

Abstract

The invention discloses a method for detecting shield channel influence area karst under a building. A horizontal directional drilling machine is utilized to horizontally drill holes in the peripheryof a channel to be built, then in a receiving well, an ultrasonic wellbore imager performs cross-hole pullback in drill holes as an acoustic source, and cross-hole acoustic waves acquired by the ultrasonic wellbore imager are acquired through a data acquisition instrument to form CT input data; and acoustic wave tomographic inversion is performed on the CT input data, mapping software is utilizedto display a cross-hole acoustic wave tomographic map, and finally, a karst distribution situation in a channel range under the building is analyzed based on acoustic wave velocity difference of a detection target and surrounding rock thereof and an attenuation law in an elastic wave propagation process. The karst detection method can overcome limitation of site conditions, an anti-interference capability is high, detection precision and resolution are high, a karst development situation in the subway tunnel range under the building can be precisely detected, risks of construction of the tunnel underneath passing the building are reduced, and the method has good social benefits and economic benefits.

Description

technical field [0001] The invention relates to the technical field of karst detection, in particular to a karst detection method in the area affected by a shield tunnel under a building. Background technique [0002] my country's rail transit has entered a stage of rapid development in recent years, and the construction of subways has been fully rolled out in major cities. However, while the number of subway lines continues to increase, it is unavoidable that the lines pass through buildings. In the karst-developed area, karst has a great impact on the subway passing through buildings. Detection plays a very important role in ensuring the safety of tunnel construction. [0003] In actual engineering, drilling is usually used to detect the development of karst. Although the accuracy is the highest, it will significantly increase the project cost. In order to make the project more economical, karst detection is often carried out by drilling combined with geophysical prospec...

AI Technical Summary

Problems solved by technology

[0003] In actual engineering, drilling is usually used to detect karst development. Although the accuracy is the highest, it will significantly increase the project cost

In order to make the project more economical, karst detection is often carried out by drilling combined with geophysical prospecting to meet the construction accuracy requirements, such as cross-hole CT, geological radar, high-density electrical methods, etc. have been widely used; however, in In the case of important buildings, there are many metal pipelines and electromagnetic interference nearby, and drilling and conventional geophysical prospecting cannot be implemented due to site restrictions or the accuracy cannot meet the requirements. When karst development cannot be clearly detected, karst will not be effectively treated. , As a result, engineering accidents such as uneven settlement of buildings, surface deformation, tunnel water gushing, and shield machine heading are likely to be caused during the construction of the subway tunnel.

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