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Geological heritage is an important part of natural resources. Properly handling the relationship between protection and utilization of geological heritage in a high urbanization level area is one of the ecological measures to promote the high-quality development of new urbanization. However, the low level of geological heritage survey, unclear family background, lack of standard classification scheme and overall evaluation restrict the effective development of geological heritage protection and utilization in Tianjin. Based on the latest data of the whole Tianjin geological heritage survey, and through the integration of previous geological heritage survey results, this paper classifies the types of geological heritage according to the Specification for Geological Heritage Survey （DZ/T 0303—2017）. The scientific research value, ornamental value and protection value are qualitatively analyzed, and the quantitative evaluation and grade division are carried out by combining expert scoring and AHP. According to the classification scheme in the Specification for Geological Heritage Survey （DZ/T 0303—2017）, the important geological heritages in Tianjin are divided into 3 main categories: basic geological category, geomorphic landscape category and geological disasters, 7 categories: stratigraphic section, important rock and ore producing areas, rock and soil geomorphology, structural geomorphology, water geomorphology, coastal geomorphology and geological disaster heritages, 10 subclasses: stratotype (typical section), typical deposit outcrop, intrusive rock landform, clastic rock landform, carbonate rock landform, wetland, klippe, fault cliff, marine landform and land subsidence. The comprehensive evaluation and analysis indicate that there are 4 world-level, 3 national-level and 8 provincial-level geological heritages in Tianjin. The above research is expected to provide references for the protection and utilization of geological heritages in Tianjin.

The structural characteristics of karst conduit have an important influence on the rational use and protection of karst water resources and the safe construction of underground engineering. At present, when using tracer test curve to analyze the structural characteristics of karst conduit, there are some problems, such as curve superposition shape, blunt front shape, irregular rise and fall of curve, connection relationship between multiple karst conduit, location of underground lake and groundwater state. In this paper, the time concentration curve of tracer test is used to explain the structural characteristics of karst conduit through the numerical simulation of the karst conduit flow tracer test and the change of water flow state. The results are as follows: (1) The number of curve peaks corresponds to the number of karst conduit, and there are three models for the parallel curve of double pipelines due to the difference of the length and velocity of karst conduit runoff. (2) The number of single karst conduit curve decline gradients corresponds to the number of blue hole, and the relationship between the decline gradients and the number of blue hole should be analyzed for multiple karst conduit in combination with the number of karst conduit and the location of blue hole. There are four types of parallel karst conduits. (3) The rapid change of curve shape indicates the mutual transformation of surface flow and pressure flow.