Case Study: Silent Rock Demolition on Qingdao Metro Line 9 Using Stone Cracking Powder

💡 Project Overview: During the excavation of the Qingdao Metro Line 9 (Xijing Station), contractors faced 148 MPa hard rock located dangerously close to a working dairy farm and an industrial plant housing vibration-sensitive precision instruments. This case study demonstrates how Stone Cracking Powder (HSCA) provided a 100% silent, non-explosive solution.

The Challenge: Extremely Hard Rock in a Complex Environment

As excavation for the subway station's entrance began, the construction crew immediately hit a massive layer of Cretaceous volcanic rock.

"It was exceptionally hard. Just three meters down, we encountered rock with a compressive strength of up to 148 MPa. That's equivalent to over 1 ton of weight pressing down on a nail head," explained Jiang Xiaowei, the project manager at Xijing Station.

Conventional methods for subway foundation pits typically involve hydraulic breakers or dynamite blasting. However, neither was possible here. Just north of the site sat a precision manufacturing plant with vibration-sensitive machinery. To the south lay a dairy farm housing over 700 cows, where blasting noise and seismic shock would severely disrupt milk production. Furthermore, spatial limitations meant large heavy machinery simply couldn't fit into the narrow excavation trench.

The Solution: Non-Explosive Demolition Agents

After multiple safety reviews, the engineering team abandoned conventional excavation methods and deployed Soundless Cracking Agents (Expansive Mortar) to fracture the 148 MPa rock silently.

The process was straightforward yet highly effective. Workers used Pneumatic Rock Drills to bore a specific pattern of holes into the bedrock. They then mixed the Stone Cracking Powder with water to form a fluid slurry and poured it into the boreholes.

💡 Engineer's Tip: Estimating Material for Deep Excavations

In deep foundation pits, accurate material estimation is critical to maintain the excavation schedule. Project engineers rely on tools like the HSCA Dosage Calculator to determine the exact amount of expansive mortar required based on rock hardness and hole spacing.

The Result: A "Six-Nots" Excavation Success

Without a single explosion, a foundation pit measuring 79.5 meters long, 5.5 meters wide, and 16.6 meters deep was successfully excavated in complete silence.

Li Yunting, Chief Engineer of the project, explained the physics behind the success: "Hard rock has a massive compressive strength but very low tensile strength. The Non-Explosive Demolition Agent exploits this. During hydration, it expands by about 50% in volume, creating immense outward radial pressure. When this tensile stress exceeds the rock's limits, it fractures quietly."

"We achieved what we call a 'Six-Nots' excavation: no fly-rock, no vibrations, no shock waves, no noise, no dust, and no toxic gases," Li added.

Case Study FAQs: Silent Urban Demolition

Q1: Can Stone Cracking Powder break rock with 148 MPa compressive strength?

A: Yes. Because rock has high compressive strength but very low tensile strength, the massive outward pressure (up to 120 MPa) generated by expansive mortar easily tears the rock apart from the inside out.

Q2: Is expansive mortar safe to use near vibration-sensitive structures?

A: Absolutely. As demonstrated in the Qingdao Metro project, it produces zero seismic shockwaves, making it safe to use directly adjacent to delicate precision instruments, historical foundations, or residential areas.

Q3: Do I need heavy machinery to use chemical rock splitters?

A: No heavy hydraulic breakers are needed. You only require handheld or portable pneumatic rock drills to bore the initial hole pattern. This makes it the ideal solution for narrow or confined foundation pits.

Facing a Complex Urban Demolition Project?

Don't let strict noise and vibration regulations stall your progress. Contact Expandag for factory-direct Soundless Cracking Agents and professional technical advice.

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*Source: Adapted from project reports by China Railway 20th Bureau Group.