应用北京昌平及西集沙层应力仪观测资料，根据该仪器以往30 年所观测到的地震震例以及2004年12 月26 日印尼8.7 级地震的前兆特征；沙层应力仪记录的汶川8.0 级地震短临前兆过程，符合沙层应力仪多年监测实践总结出来的孕震物理模型，尤其是2008 年3 月开始出现的短临异常时间与形态的阶段性变化，临震异常特征明显，与卫星热红外等其他观测项目具有很好的时间同步性，属于汶川8.0 级地震大尺度前兆异常。

An earthquake preparation physical model was established based on observation data of sand layer stress instrument in Changping and Xiji, Beijing, earthquake precursor in the past 30 years observed by this instrument and precursor of Indonesia Earthquake (M =8.7) on December 26, 2004.The short-term and impending precursor of Wenchuan Earthquake recorded by the sand layer stress instrument was in accordance with this model.The observed short-term and impending abnormal stage change of time and shape appeared in March,2008, which was in accordance with the observation results of satellite thermal infrared and other testing methods in the aspect of time, had very obvious characters of impending earthquake anomaly.