复杂地质条件下的管槽开挖支护探讨

Discussion on Excavation and Support of Pipe Trench under Complex Geological Conditions

摘要:

管槽开挖支护是市政管道工程中需经常面对的课题。其既是工程的重难点，也是影响工程造价的重要组成部分。以深厚软弱土、全/强风化岩层、中厚砂层或卵石透水层、地下未明重要管线等情况为例，探讨在复杂地质条件下的管槽开挖支护难题。针对上述地层，通过地基注浆处理与长短支护桩设计、新型挡土板支护或引孔后回填再插入钢板桩、水下混凝土封底联合基坑外降水、逆作法开挖支护或压入式顶管等方法，可有效解决深厚软弱土场地管槽支护成本高、全/强风化岩层中压桩困难、中厚砂层或卵石透水层中坑底涌水难施工、地下未明重要管线状况下无法提前打桩等技术难题，从而保证复杂地质条件下的管道敷设。

Abstract:

Excavation and support of pipe trenches are the common issue in municipal pipeline engineering, which is not only the key and difficult point of the project, but also an important component that affects the engineering cost. Taking the deep and weak soil, fully/strongly weathered rock layers, medium thick sand or pebble permeable layers, and underground unclear important pipelines as the examples, the difficulties of pipe trench excavation and support under complex geological conditions are discussed. For the above-mentioned strata, the methods such as foundation grouting treatment and design of long and short support piles, new retaining plate support or backfilling after drilling and then inserting steel sheet piles, underwater concrete bottom sealing combined with external dewatering of the foundation pit, reverse excavation support or forced pipe jacking can effectively solve the technical problems such as high cost of pipe trench support in deep and weak soil sites, difficulty in pressing piles in fully/strongly weathered rock layers, difficulty for construction when water inrush at the bottom of pits in medium thick sand or pebble permeable layers, and inability to drive piles in advance under unknown important underground pipeline conditions, thus ensuring the pipeline laying under complex geological conditions.