diff --git a/pygrt/C_extension/include/grt/common/model.h b/pygrt/C_extension/include/grt/common/model.h
index 537fd18..2b16abf 100755
--- a/pygrt/C_extension/include/grt/common/model.h
+++ b/pygrt/C_extension/include/grt/common/model.h
@@ -23,6 +23,7 @@ typedef struct {
     size_t ircv; ///< 接收点所在虚拟层位, ircv>=1, ircv != isrc
     bool ircvup; ///< 接收点位于浅层, ircv < isrc
     bool io_depth; ///< 读取的模型首列为每层顶界面深度
+    bool srcrcv_isInserted;  ///< 震源和台站是否已经以虚拟层的形式插入
 
     cplx_t omgref;   ///< 参考圆频率, 用于计算衰减
     cplx_t omega;   ///< 圆频率
diff --git a/pygrt/C_extension/src/common/model.c b/pygrt/C_extension/src/common/model.c
index e80983d..043a897 100755
--- a/pygrt/C_extension/src/common/model.c
+++ b/pygrt/C_extension/src/common/model.c
@@ -189,7 +189,7 @@ void grt_mod1d_xa_xb(GRT_MODEL1D *mod1d, const real_t k)
     size_t ircv = mod1d->ircv;
 
     for(size_t i=0; i<mod1d->n; ++i){
-        if( i == isrc || i == ircv ){
+        if( mod1d->srcrcv_isInserted && (i == isrc || i == ircv) ){
             mod1d->xa[i] = mod1d->xa[i-1];
             mod1d->caca[i] = mod1d->caca[i-1];
             mod1d->xb[i] = mod1d->xb[i-1];
@@ -230,6 +230,10 @@ void grt_realloc_mod1d(GRT_MODEL1D *mod1d, size_t n){
 
 GRT_MODEL1D * grt_read_mod1d_from_file(const char *modelpath, real_t depsrc, real_t deprcv, bool allowLiquid){
     GRTCheckFileExist(modelpath);
+
+    if(depsrc * deprcv < 0.0){
+        GRTRaiseError("depsrc and deprcv should have the same sign.");
+    }
     
     FILE *fp = GRTCheckOpenFile(modelpath, "r");
 
@@ -390,6 +394,7 @@ GRT_MODEL1D * grt_read_mod1d_from_file(const char *modelpath, real_t depsrc, rea
     mod1d->n = nlay;
     mod1d->depsrc = depsrc;
     mod1d->deprcv = deprcv;
+    mod1d->srcrcv_isInserted = (depsrc >= 0.0 && deprcv >= 0.0)? true : false;
 
     // 记录每层是否为液体层
     for(size_t i = 0; i < mod1d->n; ++i){
diff --git a/pygrt/c_structures.py b/pygrt/c_structures.py
index cdabad4..bda9965 100755
--- a/pygrt/c_structures.py
+++ b/pygrt/c_structures.py
@@ -96,6 +96,7 @@ class c_GRT_MODEL1D(Structure):
         ('ircv', c_size_t),
         ('ircvup', c_bool),
         ('io_depth', c_bool),
+        ('srcrcv_isInserted', c_bool),
 
         ('omgref', CPLX),
         ('omega', CPLX),