## 3 Data and Method
### Method
#### 3.2.2 Cross-Section Method  
A lack of universal standards across multiple data sources such as various engineering projects and the fact that soil types varied significantly from site to site (Figure 3) make data standardization difficult. This is compounded by the geological complexity modeled. Cross-sections are then constructed by selecting boreholes and combining lithology records with local geology to ensure consistency among unevenly distributed drill holes. This method comprises three major steps: (a) data digitalization, (b) lithology generalization, and (c) layer connection. (a) Data digitalization  
Existing boreholes were digitalized from original paper files. Data compilation was based on \"Norm for digitalization of text-graphic geological data in scan (SZ1999001--2000)\" released by the Information Center of Ministry of Land and Resources of People's Republic of China (ICMLR) and \"Technical requirements for the construction of the national important geological borehole database\" formulated by the China Geological Survey (CGS). The following steps are necessary to complete data digitalization accurately:  
* Checking original paper files and new borehole information. Describing the specific position of different layers, including top and base depth, coordinates (x, y, z), etc. * Comparing each lithology record with that of other boreholes in the near vicinity, especially of its nearest neighbors. If the target soil type recorded in one borehole is consistent with that of surrounding boreholes at a similar depth, the soil name of the target layer would be followed or would be treated as a lens. * Attribute data verification. This is a further validation by geotechnical parameters, which are generally relative to soil types. The properties of each type of soil normally have a specific attribute value range, for example, the natural water content of silty clay is generally between 15 and 40%, while the plastic limit value is mainly between 12 and 23%. Therefore, property values can be used as a further check on the consistency of  
Figure 3: Original boreholes and stratigraphy were recorded along the WE08 cross-section line. the lithology. Records that seemed to be in some way unreliable were noted and then discarded. (b) Data generalization  
Soil type records were likely to be inconsistent in criteria, for example, sub-clay recorded in one report but silty clay or sandy clay in another. In addition, transitional soil types, such as silty sand with partially silty clay, were quite common (for example, borehole records on Figure 3). Therefore, lithology generalization is conducted prior to cross-section connection. In this study, a total of 6 categories (artificial ground, clayy silt, silty clay, silt to fine sand, medium to coarse sand/gravel) was generalized by combing similar sediment descriptions. Soil type descriptions such as silty clay, heavy silty clay, and sub-clay were uniformly merged into \"silty clay\", records such as sandy silt, silt, and fine sand were generalized into a \"silt-fine sand\" category, while gravelly sand, coarse sand, medium-coarse sand, and gravel were merged into a \"medium to coarse sand or gravel\" category. Stratigraphic layers then were coded with unique numbers. This was done by comparing the lithology records within the boreholes to the regional stratigraphic framework and assigning layers depending on the thickness and sequence of sediment descriptions within each borehole. For example, through generalization, soil layers of borehole 043542-1 from the top downward were artificial ground (layer 10), clayy silt (layer 22), silt to fine sand (layer 24), clayy silt (layer 32), silty clay (layer 33), silt to fine sand (layer 34), silty clay (layer 43), silt to fine sand (layer 44), silty clay (layer 53), and two lenses (lens cl and lens fn) (Figure 4). Figure 4: Lithology generalization; an example from borehole 043542-1. (c) Layer connection  
Choosing a marker layer is a key step in this procedure.