北海沙坝沉积地层场地建筑物地基的岩土工程分析评价

发布时间：2018-01-08 17:35

本文关键词：北海沙坝沉积地层场地建筑物地基的岩土工程分析评价　出处：《中国海洋大学》2013年硕士论文　论文类型：学位论文

【摘要】：随着社会经济的增长,沿海工程建设向海岸带发展。北海三面环海,陆域土地空问发展有限,工程建设向海岸带(北部海岸、南部海岸、外沙岛)发展。外沙岛位于北海市北岸,四面环海,呈带状,是中全新世海侵在下更统湛江组(Q,Z)地层上沉积形成的海相沉积沙坝,晚全新世海岸抬升形成了一级海积阶地,沙坝与海岸间形成了泻湖沉积。外沙岛沙坝的基底为下志留统灵山群第二组的砂岩,基底岩石埋置深度80～100m,从下至上覆有第三系南康组(Nn)上部为粘土,中部以砂砾石和粗砂为主,下部以粘土为主夹有砂砾层、第四系下更新统湛江组(Q1z)砂砾层、第四系中全新统(Q4)松散层。外沙岛沙坝处于北海市地下水系统的排泄区(带),地下水由南向北径流,排于海域之中。场地地下水分潜水及承压水两种类型。场地潜水主要接受海水渗透补给及降水补给,承压水通过岩性天窗接受潜水的越流补给及陆域的排泄补给,承压水之间有水力联系,且水位亦受潮汐效应影响。潜水为咸水,明显受到海水入侵混合影响。通过钻探取样、标准贯入试验、圆锥动力触探试验、土工试验等岩土工程测试技术,获得各个土层的物理力学性质,运用土力学、工程岩土学、水文地质学等研究方法,在定性分析的基础上进行定量分析,作出各岩土层的岩土性质评价。分析基础方案,结合地下室功能、结构及防渗要求,认为桩筏联合基础是比较适宜该场地的基础形式,以④层土为桩端持力层。桩基及筏板均要做防渗、防腐措施。分析基坑工程方案,通过定性分析选出支护结构的类型及计算其嵌入深度；通过渗透变形分析计算及涌水量计算,确定悬挂式止水帷幕的嵌入深度及降水方式为坑内降水。提出修建挡浪墙及在基坑与海之间采用隔水帷幕减少海浪及海水侧向渗透力的影响。北海外沙岛沙坝沉积地层场地建筑物地基的岩土工程条件有其地域的特殊复杂性：上部第四系海相沉积砂层较松散,力学性质差,在地震作用下饱和砂土有液化的可能,湛江组顶部粘土隔水层受剥蚀缺失,使第四系海相沉积松散砂层的潜水含水层与湛江组砾(粗)砂的Ⅰ承压含水层相通,造成上部含水层超过30m,地下水位接近地面,地下水与海水有密切的水力联系。另外,外沙岛沙坝场地受潮汐、海浪、风暴潮、海水等海洋水文环境条件的影响,建筑地基基础施工需要考虑潮汐、海浪、风暴潮、海水侧向渗透力的影响。本课题通过外沙岛沙坝场地建筑地基的岩土工程条件分析,研究该场地建筑基础方案、基坑工程方案及海水与地下水的防治措施。为沙坝沉积地层场地建筑物地基的地基基础及基坑工程设计、施工提供参考。
[Abstract]:Along with the growth of the social economy , the coastal engineering construction is developing to the coastal zone . The North Sea is located on the north bank of the North Sea . The outer sand island is located in the north bank of the North Sea . The outer sand island is located on the north bank of the North Sea . The four sides of the Huanghai Sea are in the form of a strip . The basement of the sand bar on the outer sand island is the sandstone of the second group of the Lingshan Group , the lower Zhiliu Series , the burial depth of the basement rock is 80 ~ 100m , the upper part of the Tertiary Nankang Formation ( Nn ) is the clay , the middle part is mainly composed of sand gravel and coarse sand , the lower part is mainly composed of sand gravel layer and coarse sand , and the lower part is the sandy gravel layer with clay as the main part , and the fourth system is the Holocene ( Q1z ) sand gravel layer , and the Quaternary middle Holocene ( Q4 ) loose layer . The sand bar of the Outer Sand Island is located in the drainage area ( belt ) of the groundwater system in the North Sea . The groundwater flows from the south to the north and is discharged into the sea area . The ground water is divided into two types : sea water infiltration and recharge , and the water level is influenced by the tide effect . The diving is salty water , which is obviously affected by the seawater intrusion . Through drilling sampling , standard penetration test , cone dynamic penetration test , geotechnical test and other geotechnical test techniques , the physical and mechanical properties of each soil layer are obtained . Based on the analysis of foundation scheme , combined with basement function , structure and anti - seepage requirements , it is concluded that the foundation of pile raft foundation is the foundation form suitable for the site , and the pile foundation and raft board should be anti - seepage and anti - corrosion measures . Based on the analysis of seepage deformation and the calculation of water inflow , it is determined that the embedded depth and the precipitation method of the suspended water - stop curtain are in the pit . The influence of the water - proof curtain on the lateral seepage of sea wave and seawater is proposed by using the water - proof curtain between the foundation pit and the sea . The soil engineering conditions of the building foundation in the sand dam sedimentary formation in the sand island of the North China Sea have the special complexity of the area : the upper Quaternary marine sedimentary sand layer is loose , the mechanical property is poor , and the saturated sand in the upper part of the Zhanjiang Formation is affected by the erosion , so that the water - bearing layer of the Quaternary marine sedimentary loose sand layer is affected by the conditions of marine hydrological environment such as tide , sea wave , storm tide and sea water , and the construction foundation construction needs to take into account the influence of tide , sea wave , storm tide and seawater lateral seepage force . Based on the analysis of the geotechnical conditions of the building foundation of the sand dam site in the outer sand island , the paper studies the construction foundation scheme , the foundation pit engineering scheme and the prevention and control measures of the sea water and groundwater , and provides a reference for the foundation of the foundation of the building foundation and the engineering design and construction of the foundation pit .

【学位授予单位】：中国海洋大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：TU470

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