卵石层路基初至层析成像和多道面波联合探测技术

First-Arrival Tomography and Multi-Channel Analysis of Surface Waves Combined Detection Technology for Pebble Layer Roadbed

摘要: 为保证道路路基结构的稳定性，需要获取高精度的基岩面分布信息。在含有卵石层的区域因存在大量坚硬石块，工程钻探作业开展困难，零星布设的钻孔难以获取连续的基岩面信息，通常采用高分辨率地震探测技术来获取全面的地下结构信息。本文为解决某狭长山谷卵石层路基下基岩面探测问题，提出应用初至波层析成像和多道面波(MASW)两种浅层高分辨地震方法联合反演狭长山谷地形工区下基岩面深度及分布情况。本次沿山谷走向布设三条长测线，与之近垂直方向布设两条短测线，分别获取初至波以及面波信息。反演结果表明，该场地东西方向基岩面起伏较小，与地形近乎一致，埋藏深度由东向西减小，最深处14 m，最浅处6 m；南北方向基岩面起伏较大，南段埋藏深度略小于北段，最深处12 m，最浅处9 m。

Abstract: In order to ensure the stability of the roadbed structure, it is necessary to obtain high-precision information on the distribution of bedrock surface. In the area containing the pebble layer, due to the existence of a large number of hard stones, engineering drilling operations are difficult to carry out, and it is difficult to obtain continuous bedrock surface information from the scattered holes. High-resolution seismic detection techniques are often used to obtain comprehensive information on underground structures. In this paper, the problem of detecting the bedrock surface under the cobble layer of a narrow valley is solved. The shallow-layer high-resolution seismic method using the First-arrival Tomography and Multi-channel Analysis of Surface Waves (MASW) is proposed to jointly invert the subsurface rock surface of the narrow valley topography. Three long lines are arranged along the valley, and two short lines are arranged in the vertical direction to obtain the first arrival waves and the surface waves information respectively. The inversion results show that the bedrock surface in the east-west direction of the site is less undulating and nearly identical to the terrain. The burial depth decreases from east to west, with the deepest point being 14 m and the shallowest at 6 m. The bedrock surface in the north-south direction is undulating, the burial depth in the southern part is slightly smaller than that in the north, the deepest part is 12 m, and the shallowest is 9 m.