海口市江东新区滨海相沉积地层工程地质特性及溶蚀空洞成因分析  

Engineering Geological Characteristics and Genesis Analysis of Coastal Sedimentary Strata and Dissolution Cavities in the Jiangdong New Area,Haikou City

作　　者：王晓晗 李惠 齐信 张彦鹏 张再天 WANG Xiao-Han;LI Hui;QI Xin;ZHANG Yan-Peng;ZHANG Zai-Tian(Wuhan Center,China Geological Survey(Geosciences Innovation Center of Central South China),Wuhan 430205,Hubei,China;China Geological Survey,Beijing 100037)

机构地区：[1]中国地质调查局武汉地质调查中心(中南地质科技创新中心),湖北武汉430205 [2]中国地质调查局,北京100037

出　　处：《华南地质》2025年第1期197-206,共10页South China Geology

基　　金：中国地质调查局项目(DD20221734、DD20190304、DD20243424)。

摘　　要：海口市江东新区大部分隐伏分布的滨海相沉积地层海口组(N2h)主要由半松散、半成岩的贝壳碎屑岩与贝壳砂砾岩组成,孔隙极为发育,透水性强,容易产生地下空洞,引发空洞塌陷等工程地质问题。基于此,本文首先对海口组的空间分布特征进行了分析,然后以这两种岩石为研究对象,测试了它们的基本物理性质和水理性质指标,并开展了天然和饱水状态下的力学试验,总结了两种岩石的工程地质特性,对其产生的地下空洞的分布特征与成因也进行了初步分析。结果表明:(1)海口组的顶板埋深4.6~44.4 m,从北西往南东方向越来越浅,且中部区域比北、西、南三个区域浅,两种岩石主要分布在海口组一段和三段中;(2)两种岩石内部的孔隙和裂隙较多,单轴抗压强度平均值分别为24.82、21.46 MPa,软化系数平均值分别为0.58、0.51,遇水软化效应非常明显;(3)两种岩石易溶蚀的特性导致其分布区易产生溶蚀空洞,主要发育在江东新区起步区和云龙-演丰一带;其形成机制首先是两种岩石在沉积胶结的过程中即形成了空洞,然后,地下水溶蚀作用导致空洞进一步发育和扩大。本研究可为海口江东新区的工程建设提供参考。The majority of the hidden coastal sedimentary strata in Jiangdong New Area,Haikou City,from the Haikou Formation(N2h),are mainly composed of semi loose and semi diagenetic shell clastic rocks and shell glutenite.The pores are extremely developed,with strong permeability,and it is easy to produce underground cavities,leading to engineering geological problems such as cavity collapse.Based on this,the spatial distribution characteristics of the Haikou Formation were firstly analyzed,and then,the basic physical and hydraulic properties of two types of rocks as the research objects were tested.The mechanical tests were conducted separately under natural and saturated conditions to study the engineering geological characteristics of the rocks.The preliminary analysis on the distribution characteristics and causes of the underground cavities were also conducted.The results show that:(1)The burial depth range of the roof of the Haikou Formation is 4.6-44.4 m,gradually being shallower from northwest to southeast,and the central region is shallower than the north,west,and south regions.The two types of rocks are mainly distributed in the first and third sections of the Haikou Formation;(2)There are many pores and cracks inside the two types of rocks,with average uniaxial compressive strengths of 24.82 and 21.46 MPa,and average softening coefficients of 0.58 and 0.51,respectively.The softening effect is very obvious when encountering water;(3)The characteristic of easy dissolution of two types of rocks leads to the formation of dissolution cavities in their distribution areas,mainly developed in the starting area of Jiangdong New Area and the Yunlong-Yanfeng area.Cavities form during the process of sedimentary cementation of two types of rocks and then the dissolution of groundwater leads to further development and expansion of the cavities.This study can provide reference for the engineering construction of Jiangdong New Area in Haikou city.

关 键 词：海口组 贝壳碎屑岩 贝壳砂砾岩 工程地质特性 力学性质 水理性质 溶蚀空洞 

分 类 号：P642[天文地球—工程地质学]