The compression modulus of sandy soil exerts influence on the stability of sandy soil surrounding rock of tunnel. From the perspective of influential factors of the stability of sandy soil surrounding rock and the stability classification of surrounding rock
the influential factors of compression modulus which are related to the stability of sandy soil surrounding rock
are explored. It is discovered that the clay content (d <0.074 mm) of sandy soil has distinct influence on the compression modulus of sandy soil; The relationship between the compactness and compression modulus is not always a direct ratio which is relevant to the clay content of sandy soil and water content of clay. It is held that it is more rational to adopt the water content of clay rather than water content of sandy soil to access the compression modulus of moist sandy soil. Recommended limits of content of clay and compactness for surrounding rock classification are advanced in accordance with the relationships between compression modulus and content of clay