Abstract：Because the physicochemical soft rock has such physico-mechanical properties as hydrate swelling，strength debase and softening disintegration etc.，conventional supporting system cannot bear enormous expanding and disintegration stresses，and an anchor point can¢t be found in the anchoring system，so that supporting and anchoring system fail in engineering of physicochemical soft rock. Taking No.1 coal seam floor shale with a high montmorillonite content of Wali mine in Longkou，Shandong Province，for example，a new fashioned solidification at ambient temperature silicon modified resin is synthesized by radical solution copolymerization and sol-gel method in laboratory；and the surface coated modification effect of soft rock is researched by comparative tests on coatings hydrophobic property，fastness，waterproof and rock samples particle free swelling，block disintegration before and after modification. The results indicate that adhesion of interface between coating and surface of rock samples is excellent，contact angle of water drop on the rock samples surface increases from 26.40° to 80.04°，while water absorption of rock samples decreases from 41.87% to 3.15%，the free swelling ratio of rock sample particles decreases from 24.11%–65.98% to 1.64%–3.60%，and the fractal dimension of rock sample block disintegration grains distribution decreases from 2.223 1–2.716 2 to 0.300 7–2.389 5.
