Abstract:

In view of the problem of material pregrouting reinforcement in urban metro crossing sand layer, the gel time, gel form, influencing factors of strength of sand consolidation material of phosphoric acidwater glass grouting material and engineering application ratio of materials are studied. Laboratory test on gel properties of phosphoric acid water glass grouting material and test on compressive strength of soil consolidation are designed and compared with those of traditional sulphuric acid water glass grouting material. After that，field tests are carried out. The test results show that: 1) With the increase of the concentration of phosphoric acid, the volume ratio of phosphoric acid and sodium silicate increases, the pH value of mixed liquor decreases and the gel time increases. 2) The pH value of the mixed solution of phosphoric acid water glass is the decisive factor of the gel time and the gel shape. 3) The variations of phosphoric acid concentration, water glass Baume and volume ratio of mixed liquid in phosphoric acid water glass grout have a little effect on the compressive strength of the consolidation body.

Key words: metro, sand layer, pregrouting reinforcement, phosphoric acid water glass, gel time, pH value, compressive strength of sand consolidation body